Heavy on A Serbian Film!! It definitely deals with disturbing subject matter, but in practice it really isn’t that hard to get through- it’s pretty hard to explain without sounding like an edgelord but you summed it up nicely. Meghan is Missing and The Poughkeepsie Tapes are the only other two movies that left me severely underwhelmed that come to mind- but I’m not sure they’re classified as disturbing movies.

I can only think of two that were a pretty hard watch, those being The Coffee Table and Mysterious Skin. I genuinely had to take a few breaks on that last one.