On frwiki, the following search query (as of today) gives me one result (Utilisateur:Garfieldairlines/monobook.css):
(actually the "intitle" filter is only to emphasize the issue)
But if I add a contentmodel filter, the result is missing:
insource:DeluxeBar intitle:Garfieldairines contentmodel:css
The index for this page hasn't been updated since content models were added, so an edit to the page will update it, and we'll look at taking care of the issue at a more global level
The reindexing will be resolved by T203622. The first pass through should be finished mid-december which will reindex all pages missing content models.