Nextcloud AIO becomes unresponsive even though all containers are healthy

Glad for clarifying.
Yes, I would be comfortable running read-only SELECT queries, as long as they are provided explicitly and don’t modify anything in the database.

I’m not confident enough to come up with queries myself, but I can copy/paste and share the results back here.

My Nextcloud is down again.
You can check logs from nextcloud-aio-nextcloud here - nextcloud-freeze-logs - Pastebin.com

Disabling the Federation application apparently didn’t help.