Steps to Reproduce:
Move a translatable page that has at least one outdated translation unit (this happened on MediaWiki.org when I moved https://www.mediawiki.org/wiki/Wikia to https://www.mediawiki.org/wiki/Fandom)
All previously-outdated translations are no longer marked as outdated. For example, see https://www.mediawiki.org/w/index.php?title=Fandom/ru&diff=prev&oldid=4418282
Any translation units that were outdated before making the move stay outdated.
Information about translation status is no longer lost during a move of a translatable page.