iCloud sync stuck

What I’m trying to do

My vault on iCloud stopped syncing between my Mac and my iPhone. I can see stalled (stuck) uploads and downloads when clicking to info icon on my iCloud drive on the Mac.

Things I have tried

I tried to restart the Mac - it did not help
I tried to kill the “bird” process on the Mac several times. It seemed to help at first but now it does not work at all.
Is there any solution to get rid of this annoyng problem? Thanks

There are existing threads on this forum if you try the search field.

I did not find anything that would solve the problem…