This is probably what I'm doing wrong. I'm using linuxserver's docker which should be okay to auto update, but it just continuously degrades over time with updates until it becomes non-functional. Random login failures, logs failing to load, file thumbnails disappearing, the goddamn Collabora office docker that absolutely refuses to work for more than one week, etc.
I just nuke the NC docker and database and start from scratch every year or so.
I'm absolutely at that point with Nextcloud. I kind of didn't want to go the syncthing route, but I'll probably give it a shot anyway since none of the NC alternatives seem any better.