Primarily the audience. The artist can approach a project with a certain set of ideas, precepts, and motivations, and attempt to communicate something, but the interpretations of the audience supercede that IMO.

That said, there’s different levels of engagement that inform different interpretations. Not the best example, but there’s some folks who watched Starship Troopers, for instance, who didn’t get that it was intended as satire until they listened to the director’s commentary. This does have an impact on interpretive activity when engaging with that knowledge - all of a sudden, certain things lend themselves to closer consideration. I do think there’s such a thing as informed and uninformed interpretation, though ideally a work stands on its own without reference to paratext/the creator’s claims.

Edit: Good counter example - The Room. Intended as a serious attempt at Tennessee Williams-esque drama, widely interpreted as an experiment in a sort of cringe comedy, seeing the reaction the writer/director/lead decides to roll with that.