Off-topic perhaps but after you have recovered your Nextcloud deployment …
This seems to happen to me every couple of years
Worth considering some kind of free space monitoring?
Various server monitor apps/agents, but simplest is a bash script run as a cron using ntfy to send alerts.
I get a daily notification of disk free space, and an “intra-day” alert if anything spikes over a set level.
I’m not judging, been there too, but poking yourself in the eye repeatedly doesn’t seem a good idea. Incidents happen, I know, the trick is to learn from them. ‘Root cause’ ‘corrective action’ blah blah blah