Reported here https://community.metabrainz.org/t/search-results-improvements/387195/29?u=samj1912

justcheckingitout says:

Separate from the “results could be expanded” issue…

I have noticed that sometimes search switches languages on me.
No, I have not noticed a pattern. It just seems to, at random times, say:
Recherche indexée
Recherche indexée avec la syntaxe de requête approfondie
Recherche directe dans la base de données

Searching again brings it back to english.