Trigger junk move by Subject line impacts forwarded emails
The "Move Spam Emails to Junk folder" option creates a sieve filter line that targets the Subject line of the mail:
if anyof (header :contains "X-Spam-Flag" "YES", header :contains "X-Spam" "Yes", header :contains "subject" "*** SPAM ***", header :contains "subject" "***SPAM***")
The problem with the subject line is, that if such an email (e.g. a false positive) is being forwarded to another user, it ends up again in the Junk folder, because the subject still matches the "*** SPAM ***", as long as the user didn't remove it manually.
I suggest to remove the subject check, but only rely on header lines added by rspamd (and spamassassin), e.g. by adding the check
header :contains "X-Spam-Status" "yes" too.