Currently text reparser handles text depending on BBCode options and flags. Some options are being set depending on the text is having phpBB 2 or 3 parsed bbcode entries or not.

But there're cases when text is having BBCode tags saved as plain text (f.e. BBCode was disabled, broken upgrade/conversion etc.) and it is necessary to reparse them to get BBCode formatted text back. Example support topic: https://www.phpbb.com/community/viewtopic.php?t=2656969.