Watch Ultra 2 (10.1) displays spinning clock all the time

I know of the battery draining issue with fw 10.1, mine does that too.

But my Ultra 2 also falls back to displaying the little spinning clock all the time, since updating to WatchOS 10.1.

I know of the suggested solutions: unpair and re-pair / reset / restore factory settings. But NONE of these solve the issue.

Even after a total fresh configuration (done that multiple times) and changing / installing absolutely nothing after that, my watch displays the spinning clock as if something is loading all the time.

So I have a new expensive watch that I can't use. It was fine before 10.1.