Welp, took a quick check of his TMDB profile and I think I have your answer: the name on his TMDB profile's been changed as well.

https://www (.) themoviedb (.) org/person/131-jake-gyllenhaal-aws (remove the spaces and parentheses. Mycast staff put a ban on most links thanks to spambots so I have to change it up a little to actually get it to comment.)

I've seen this kind of stuff happen a few times. A while ago, James Carter Cathcart's original actor page had its name changed to Jennifer Douillard at random, so it doesn't show up under his actual name anymore, and voice actress/singer Amanda Lee's main actor page had its name changed to Amanda Lee Wai-Man because I guess someone over there got her confused with the similarly-named pop singer from Hong Kong. Like wikis and IMDB, I believe TMDB is user-edited and thus, trolls and misguided edits happen. Unfortunately, said trolling or misguided edits tend to have wide reaching consequences. Alternatively, I wonder if some wires got crossed in their database or whatever and whatever hooked their TMDB profiles to their Mycast ones got changed, thus giving them the wrong actors? Either way, most of these actor name profile problems are mainly TMDB-related issues, so there's not much we can do about it, I think.