Using clamav-milter 0.103.1 with sendmail on Fedora 33, we had several emails quarantined with the MBL_82485625.UNOFFICIAL. All they contained was a link forwarded as an attachment of a Google Drive folder. I reported this to the false positive at SaneSecurity address. I also added the signature to a file called  /var/lib/clamav/sigwhitelist.ign2