Backup fails with postgres 18

I made a quick test with an external postgres 18 and a dummy discourse installation before, it showed no issues. But, to be honest, this was only “quick and dirty”, not a “deep” test. Anyway, it runs since 2 weeks, so I assume its fine. The Discourse-internal backup is the only issue so far. On the other hand, the database server itself (running on LXC) is also backuped separately.