Does the NextCloud client still support OwnCloud?

I’ve been using the NextCloud client for years to connect to an ownCloud server (alongside another NextCloud server) - so far without a problem. However, starting a few days ago I was logged out of the OwnCloud in the NextCloud client, I get an error message that the login failed, the server responded ‘precondition failed’.

Did either NextCloud or ownCloud drop support for each other? Is there a fix for this? I really liked that they were compatible until now and I don’t want to have to install yet another cloud service on my computer :confused: