Noticed in mediawiki-errors for both wmf.8 an wmf.9
[XBuw4QpAICMAALTXkHkAAABG] /w/index.php?title=Speci%C3%A1lis:Lap_%C3%A1tnevez%C3%A9se&action=submit MediaWiki\Revision\RevisionAccessException from line 1643 of /srv/mediawiki/php-1.33.0-wmf.8/includes/Revision/RevisionStore.php: Main slot of revision 20798212 not found in database!
[XBuxngpAIDgAAJFITF8AAADO] /w/api.php?rvprop=userid%7Cuser%7Cids%7Ccontent%7Csize%7Ctimestamp%7Ccontentmodel%7Ccomment&revids=815943409&prop=revisions&format=json&rvslots=main&action=query MediaWiki\Revision\RevisionAccessException from line 1643 of /srv/mediawiki/php-1.33.0-wmf.9/includes/Revision/RevisionStore.php: Main slot of revision 815943409 not found in database!
Impact
Through the API, querying information about some pages results in an internal_api_error response.