Hello cummunity. Thanks for your attention.
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(?). All accounts use of course the very same password. 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 and the affected Nextcloud-instance is provided by Murena.
I appreciate your ideas to solve this problem.