Ok, did some more investigation because the map error (https://discuss.freedombox.org/t/issues-with-rspamd/3920) hasn’t disappeared.
On a mailcow post (https://community.mailcow.email/d/5394-rspamd-ssl-connect-error-syscall-fail-connection-reset-by-peer/13) I found the maps problem is related to an outdated rspamd version. With rspamd version 3.13.0 the issue should be fixed. FreedomBox is currently running rspamd version 3.12.1.
Maybe the fuzzy error is related to to the same issue with maps and gets fixed with the update. So I need to wait for rspamd 3.13.0 on FreedomBox.
If anybody has more information, let me know.