This is happening on Koha 20.05.05, similar to [24146] bug https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=24146 if a library writes off an accruing fine and then checks that item in, that fine will be re-charged to the patron as Fine Returned.
I'm struggling to replicate this.. was it really only on 20.05 or could you also replicate it on master?
(In reply to Martin Renvoize from comment #1) > I'm struggling to replicate this.. was it really only on 20.05 or could you > also replicate it on master? We had no other reports of this, neither has it been confirmed. 20.05 is no longer maintained. Marking WORKSFORME. Please reopen if this bug is still present for you in maintained versions.