I spotted the following in the logspam.
Warning: According to a SiteLinkLookup Q47013093 is linked to frwiki while it is not or it does not exist. [Called from Wikibase\Client\ParserOutput\ClientParserOutputDataUpdater::setBadgesProperty in /srv/mediawiki/php-1.31.0-wmf.12/extensions/Wikibase/client/includes/ParserOutput/ClientParserOutputDataUpdater.php at line 126] in /srv/mediawiki/php-1.31.0-wmf.12/includes/debug/MWDebug.php on line 309
After the patch altering the logging these exist as below:
According to SiteLinkLookup Q9896024 is linked to itwiki, but the link does not exist.
We should probably investigate this and figure out what ha happened, and if there is a fix that is needed.