⧼config-mysql-old⧽ is being output verbatim when running update.php if your MySQL version is too old (I set $minimumVersion to 50.5.8 for testing)
$ php maintenance/update.php MediaWiki 1.32.0-alpha Updater Your composer.lock file is up to date with current dependencies! ⧼config-mysql-old⧽
This is rather unhelpful, as it doesn't tell you any useful information about what version you're running, nor what version you need!
Looks to have been broken since it's introduction by @Legoktm in https://github.com/wikimedia/mediawiki/commit/574ae4929e30700e29fef0e0d4f4824599205174 for T162044