I am using previous version of client v.0.17.9.2 and running sometimes just to get sync with network and it works; "current number of blocks 1382830" with date 13 dec 2023.
after seeing your post I started client and it get 2 connection with nodes with even older version of client: v0.14.2
...but thats all, client can not get more connections and synchronise to current date - it seems it doesn't work anymore
The wallet version 21.1 seems to be stuck at block 1370647. It appears that other clients are disconnecting. I couldn't detect any fork.
Debug "Potential stale tip detected, will try using extra outbound peer"
Ehm.. Just for my better understanding.
Christian, when are you wrote "
Debug "Potential stale tip detected, will try using extra outbound peer"", did you mean you are debugging it now, or you suggest us to debug it?
I am ok with both options, but would slightly prefer the first one

I have written that to joshafest. He want to fix this problem.