(I'm trying 13.0-BETA1.) I remember someone mentioning these appearing when 12.2 came out, and someone seemed sorry/dismayed that whatever bug that caused them had slipped through, and so I'd imagined this would have been fixed for sure in 13. But there's still time! I don't remember what the proper name is for those sphere things, or what causes them to appear, but I'm sure you'll know what I'm talking about.
Edit /etc/loader.conf to: - remove (if it exists) the line "loader_logo="orbbw" (or "orb", or "beastiebw", or "beastie" - add the line "loader_logo="fbsdbw" See man 5 loader.conf.
*** This bug has been marked as a duplicate of bug 248628 ***