Hello,
I was able to update an external CentOS Linux 8.2 standalone engine from 4.4.2 to 4.4.3 (see dedicated thread).
Then I was able to put into maintenance one 4.4.2 host (CentOS Linux 8.2 based, not ovirt node ng) and run:

[root@ov301 ~]# dnf update
Last metadata expiration check: 0:27:11 ago on Wed 11 Nov 2020 08:48:04 PM CET.
Dependencies resolved.
======================================================================================================================
 Package                   Arch   Version                              Repository                                Size
======================================================================================================================
Installing:
 kernel                    x86_64 4.18.0-193.28.1.el8_2                BaseOS                                   2.8 M
 kernel-core               x86_64 4.18.0-193.28.1.el8_2                BaseOS                                    28 M
 kernel-modules            x86_64 4.18.0-193.28.1.el8_2                BaseOS                                    23 M
 ovirt-ansible-collection  noarch 1.2.1-1.el8                          ovirt-4.4                                276 k
     replacing  ovirt-ansible-engine-setup.noarch 1.2.4-1.el8
     replacing  ovirt-ansible-hosted-engine-setup.noarch 1.1.8-1.el8
Upgrading:
 ansible                   noarch 2.9.15-2.el8                         ovirt-4.4-centos-ovirt44                  17 M
 bpftool                   x86_64 4.18.0-193.28.1.el8_2                BaseOS                                   3.4 M
 cockpit-ovirt-dashboard   noarch 0.14.13-1.el8                        ovirt-4.4                                3.5 M
 ioprocess                 x86_64 1.4.2-1.el8                          ovirt-4.4                                 37 k
 kernel-tools              x86_64 4.18.0-193.28.1.el8_2                BaseOS                                   3.0 M
 kernel-tools-libs         x86_64 4.18.0-193.28.1.el8_2                BaseOS                                   2.8 M
 libiscsi                  x86_64 1.18.0-8.module_el8.2.0+524+f765f7e0 AppStream                                 89 k
 nftables                  x86_64 1:0.9.3-12.el8_2.1                   BaseOS                                   311 k
 ovirt-hosted-engine-ha    noarch 2.4.5-1.el8                          ovirt-4.4                                325 k
 ovirt-hosted-engine-setup noarch 2.4.8-1.el8                          ovirt-4.4                                227 k
 ovirt-imageio-client      x86_64 2.1.1-1.el8                          ovirt-4.4                                 21 k
 ovirt-imageio-common      x86_64 2.1.1-1.el8                          ovirt-4.4                                155 k
 ovirt-imageio-daemon      x86_64 2.1.1-1.el8                          ovirt-4.4                                 15 k
 ovirt-provider-ovn-driver noarch 1.2.32-1.el8                         ovirt-4.4                                 27 k
 ovirt-release44           noarch 4.4.3-1.el8                          ovirt-4.4                                 17 k
 python3-ioprocess         x86_64 1.4.2-1.el8                          ovirt-4.4                                 33 k
 python3-nftables          x86_64 1:0.9.3-12.el8_2.1                   BaseOS                                    25 k
 python3-ovirt-engine-sdk4 x86_64 4.4.6-1.el8                          ovirt-4.4                                560 k
 python3-perf              x86_64 4.18.0-193.28.1.el8_2                BaseOS                                   2.9 M
 python3-pyasn1            noarch 0.4.6-3.el8                          ovirt-4.4-centos-opstools                140 k
 python3-pyasn1-modules    noarch 0.4.6-3.el8                          ovirt-4.4-centos-opstools                151 k
 qemu-img                  x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        1.0 M
 qemu-kvm                  x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        118 k
 qemu-kvm-block-curl       x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        129 k
 qemu-kvm-block-gluster    x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        131 k
 qemu-kvm-block-iscsi      x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        136 k
 qemu-kvm-block-rbd        x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        130 k
 qemu-kvm-block-ssh        x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        131 k
 qemu-kvm-common           x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        1.2 M
 qemu-kvm-core             x86_64 15:4.2.0-29.el8.6                    ovirt-4.4-advanced-virtualization        3.4 M
 selinux-policy            noarch 3.14.3-41.el8_2.8                    BaseOS                                   615 k
 selinux-policy-targeted   noarch 3.14.3-41.el8_2.8                    BaseOS                                    15 M
 spice-server              x86_64 0.14.2-1.el8_2.1                     AppStream                                404 k
 tzdata                    noarch 2020d-1.el8                          BaseOS                                   471 k
 vdsm                      x86_64 4.40.35.1-1.el8                      ovirt-4.4                                1.4 M
 vdsm-api                  noarch 4.40.35.1-1.el8                      ovirt-4.4                                106 k
 vdsm-client               noarch 4.40.35.1-1.el8                      ovirt-4.4                                 24 k
 vdsm-common               noarch 4.40.35.1-1.el8                      ovirt-4.4                                136 k
 vdsm-hook-ethtool-options noarch 4.40.35.1-1.el8                      ovirt-4.4                                9.8 k
 vdsm-hook-fcoe            noarch 4.40.35.1-1.el8                      ovirt-4.4                                 10 k
 vdsm-hook-openstacknet    noarch 4.40.35.1-1.el8                      ovirt-4.4                                 18 k
 vdsm-hook-vhostmd         noarch 4.40.35.1-1.el8                      ovirt-4.4                                 17 k
 vdsm-hook-vmfex-dev       noarch 4.40.35.1-1.el8                      ovirt-4.4                                 11 k
 vdsm-http                 noarch 4.40.35.1-1.el8                      ovirt-4.4                                 15 k
 vdsm-jsonrpc              noarch 4.40.35.1-1.el8                      ovirt-4.4                                 31 k
 vdsm-network              x86_64 4.40.35.1-1.el8                      ovirt-4.4                                331 k
 vdsm-python               noarch 4.40.35.1-1.el8                      ovirt-4.4                                1.3 M
 vdsm-yajsonrpc            noarch 4.40.35.1-1.el8                      ovirt-4.4                                 40 k
Installing dependencies:
 NetworkManager-ovs        x86_64 1:1.22.14-1.el8                      ovirt-4.4-copr:copr.fedorainfracloud.org:networkmanager:NetworkManager-1.22
                                                                                                                144 k

Transaction Summary
======================================================================================================================
Install   5 Packages
Upgrade  48 Packages

Total download size: 116 M

After reboot I can activate the host (strange that I see many pop up messages about "finished activating host") and the host is shown as

OS Version: RHEL - 8.2 - 2.2004.0.2.el8
OS Description: CentOS Linux 8 (Core)
Kernel Version: 4.18.0 - 193.28.1.el8_2.x86_64
KVM Version: 4.2.0 - 29.el8.6
LIBVIRT Version: libvirt-6.0.0-25.2.el8
VDSM Version: vdsm-4.40.35.1-1.el8
SPICE Version: 0.14.2 - 1.el8_2.1
GlusterFS Version: [N/A]
CEPH Version: librbd1-12.2.7-9.el8
Open vSwitch Version: [N/A]
Nmstate Version: nmstate-0.2.10-1.el8
Kernel Features: MDS: (Vulnerable: Clear CPU buffers attempted, no microcode; SMT vulnerable), L1TF: (Mitigation: PTE Inversion; VMX: conditional cache flushes, SMT vulnerable), SRBDS: (Not affected), MELTDOWN: (Mitigation: PTI), SPECTRE_V1: (Mitigation: usercopy/swapgs barriers and __user pointer sanitization), SPECTRE_V2: (Mitigation: Full generic retpoline, IBPB: conditional, IBRS_FW, STIBP: conditional, RSB filling), ITLB_MULTIHIT: (KVM: Mitigation: Split huge pages), TSX_ASYNC_ABORT: (Not affected), SPEC_STORE_BYPASS: (Mitigation: Speculative Store Bypass disabled via prctl and seccomp)
VNC Encryption: Disabled
FIPS mode enabled: Disabled


while another host still in 4.4.2:

OS Version: RHEL - 8.2 - 2.2004.0.2.el8
OS Description: CentOS Linux 8 (Core)
Kernel Version: 4.18.0 - 193.19.1.el8_2.x86_64
KVM Version: 4.2.0 - 29.el8.3
LIBVIRT Version: libvirt-6.0.0-25.2.el8
VDSM Version: vdsm-4.40.26.3-1.el8
SPICE Version: 0.14.2 - 1.el8
GlusterFS Version: [N/A]
CEPH Version: librbd1-12.2.7-9.el8
Open vSwitch Version: [N/A]
Nmstate Version: nmstate-0.2.10-1.el8
Kernel Features: MDS: (Vulnerable: Clear CPU buffers attempted, no microcode; SMT vulnerable), L1TF: (Mitigation: PTE Inversion; VMX: conditional cache flushes, SMT vulnerable), SRBDS: (Not affected), MELTDOWN: (Mitigation: PTI), SPECTRE_V1: (Mitigation: usercopy/swapgs barriers and __user pointer sanitization), SPECTRE_V2: (Mitigation: Full generic retpoline, IBPB: conditional, IBRS_FW, STIBP: conditional, RSB filling), ITLB_MULTIHIT: (KVM: Mitigation: Split huge pages), TSX_ASYNC_ABORT: (Not affected), SPEC_STORE_BYPASS: (Mitigation: Speculative Store Bypass disabled via prctl and seccomp)
VNC Encryption: Disabled
FIPS mode enabled: Disabled

But if I try to move away VMs from the 4.4.2 host to the 4.4.3 one I get error:

Failed to migrate VM c8client to Host ov301 . Trying to migrate to another Host.
(btw: there is no other active host; there is a  ov300 host that is in maintenance)
No available host was found to migrate VM c8client to.

It seems the root error in engine.log is:

2020-11-11 21:44:42,487+01 ERROR [org.ovirt.engine.core.vdsbroker.monitoring.VmAnalyzer] (ForkJoinPool-1-worker-11) [] Migration of VM 'c8client' to host 'ov301' failed: VM destroyed during the startup.

On target host in /var/log/libvirt/qemu/c8clinet.log I see:
2020-11-11 20:44:40.981+0000: shutting down, reason=failed

In target vdsm.log

2020-11-11 21:44:39,958+0100 INFO  (jsonrpc/1) [jsonrpc.JsonRpcServer] RPC call VM.migrationCreate took more than 1.00
 seconds to succeed: 1.97 (__init__:316)
2020-11-11 21:44:40,230+0100 INFO  (periodic/3) [vdsm.api] START repoStats(domains=()) from=internal, task_id=cb51fd4a-09d3-4d77-821b-391da2467487 (api:48)
2020-11-11 21:44:40,231+0100 INFO  (periodic/3) [vdsm.api] FINISH repoStats return={'fa33df49-b09d-4f86-9719-ede649542c21': {'code': 0, 'lastCheck': '4.1', 'delay': '0.000836715', 'valid': True, 'version': 4, 'acquired': True, 'actual': True}} from=internal, task_id=cb51fd4a-09d3-4d77-821b-391da2467487 (api:54)
2020-11-11 21:44:41,929+0100 INFO  (jsonrpc/5) [api.virt] START destroy(gracefulAttempts=1) from=::ffff:10.4.192.32,52266, vmId=c95da734-7ed1-4caa-bacb-3fa24f4efb56 (api:48)
2020-11-11 21:44:41,930+0100 INFO  (jsonrpc/5) [virt.vm] (vmId='c95da734-7ed1-4caa-bacb-3fa24f4efb56') Release VM resources (vm:4666)
2020-11-11 21:44:41,930+0100 INFO  (jsonrpc/5) [virt.vm] (vmId='c95da734-7ed1-4caa-bacb-3fa24f4efb56') Stopping connection (guestagent:444)
2020-11-11 21:44:41,930+0100 INFO  (jsonrpc/5) [vdsm.api] START teardownImage(sdUUID='fa33df49-b09d-4f86-9719-ede649542c21', spUUID='ef17cad6-7724-4cd8-96e3-9af6e529db51', imgUUID='ff10a405-cc61-4d00-a83f-3ee04b19f381', volUUID=None) from=::ffff:10.4.192.32,52266, task_id=177461c0-83d6-4c90-9c5c-3cc8ee9150c7 (api:48)

It seems that during the host update the OVN configuration has not been maintained.
Right now all my active VMs are with at least a vnic on OVN so I cannot test the scenario of migrating a VM without OVN based vnic.

In fact on engine I see only the currently active host in 4.4.2 (ov200) and another host that is in maintenance (it is still in 4.3.10; I wanted to update to 4.4.2 but I realized that 4.4.3 has been out...):

[root@ovmgr1 ovirt-engine]# ovn-sbctl show
Chassis "6a46b802-5a50-4df5-b1af-e73f58a57164"
    hostname: "ov200.mydomain"
    Encap geneve
        ip: "10.4.192.32"
        options: {csum="true"}
    Port_Binding "2ae7391b-4297-4247-a315-99312f6392e6"
    Port_Binding "c1ec60a4-b4f3-4cb5-8985-43c086156e83"
    Port_Binding "174b69f8-00ed-4e25-96fc-7db11ea8a8b9"
    Port_Binding "66359e79-56c4-47e0-8196-2241706329f6"
    Port_Binding "ccbd6188-78eb-437b-9df9-9929e272974b"
Chassis "ddecf0da-4708-4f93-958b-6af365a5eeca"
    hostname: "ov300.mydomain"
    Encap geneve
        ip: "10.4.192.33"
        options: {csum="true"}
[root@ovmgr1 ovirt-engine]#

Any hint about the reason of losing OVN config for ov301 and the correct procedure to get it again and persiste future updates?

NOTE: this was a cluster in 4.3.10 and I updated it to 4.4.2 and I noticed that the OVN config was not retained and I had to run on hosts:

[root@ov200 ~]# vdsm-tool ovn-config engine_ip ov200_ip_on_mgmt
Using default PKI files
Created symlink /etc/systemd/system/multi-user.target.wants/openvswitch.service → /usr/lib/systemd/system/openvswitch.service.
Created symlink /etc/systemd/system/multi-user.target.wants/ovn-controller.service → /usr/lib/systemd/system/ovn-controller.service.
[root@ov200 ~]#

Now it seems the problem persists...
Why do I have to run each time?

Gianluca