When Special:MergeHistory is used to merge all versions of page A into page B, page A is automatically created as a redirect.
With the extension FlaggedRevs enabled, this redirect should be automatically marked as reviewed, but it isn't. Example:

• Redirect: https://de.wiktionary.org/w/index.php?title=verhalten_%28Konjugation%29&redirect=no
• Merging log: https://de.wiktionary.org/w/index.php?title=Spezial%3ALogbuch&type=merge&user=Kronf&page=verhalten+%28Konjugation%29

By contrast, redirects created by moving a page are automatically reviewed.