I assumed this is more a Nextcloud-topic. I asked the community there ten days ago but got no answer. If somebody here has an idea, I would appreciate that.
I integrated my Nextcloud Contacts into the Contacts app of macOS 12.7.5. This worked fine round about a year. Since a few weeks, macOS is permanently asking for the password. When I do provide it, the password seems to get accepted. But a minute later I am asked again, without an indication of a false entry.
This problem is true only with Contacts. I also synch Email, Calendar, Tasks and Notes. Those services are connected as several different accounts. Only the connection to Contacts is affected.
Logically, a new contact, created on my phone, appears in the cloud but not in macOS.
I use the Nextcloud Desktop-Client 3.13.2