Some more updates ....
>> Did this start after upgrading to 22.04? Or after a certain kernel
>> upgrade?
>
> For sure it only started with Ubuntu 22.04. We did not had and still
> not have any issues on servers with Ubuntu 20.04 and 18.04.
It also happens with Ubuntu 22.10 (Kernel 5.19.0-23-generic). We now try
6.0 mainline and 5.15. mainline kernel on some servers.
I also forgot to mention that /var/lib/postgresql/12 directory is
encrypted with fscrypt (ext4 encryption). So we also deactivated the
directory encryption on one server to see if it is related to
encryption.
thanks
Klaus