On Fri, Dec 11, 2020 at 7:08 AM Alex McWhirter <alex@triadic.us> wrote:

You have to put all hosts in the cluster to maintenance mode first, then you can change the compat version.

No, it never was this way. You only get a triangle on the VMs icon telling you that for that VM to aquire the change it needs to be powered off and then on again.

No full maintenance never required.