Depends on if theres a difference between transgressive shock content or films that may seem transgressive but explore topics that make it disturbing.
Most people that watch "disturbing movies" often watch the shock content part and unsurprisingly dont get disturbed. Examples include a serbian film, arguably the 120 days of sodom (I DONT KNOW HOW THIS FILM IS A CRITCISIM OF FASCISM,), slaughtered vomit dolls which is just a fetish movie,
Guinea Pig: The Devil’s Experiment probably a fetish movie idk didnt watch it. Etc they dont matter, theyre made to be transgressive and if they have a deeper meaning it just doesnt land and people walk out of the theatre disturbed for 30 minutes and then go on with their lives. These are films made for youtubers to watch and then describe the films so that you can feel disturbed whilst not harming your retinas with poop rape porn with lots of BLOOD.
On the other hand here are films I have watched and I would argue are way more distubing mostly because of the topics they discuss, you dont have to slam a gazlllion scenes of poop rape porn to make something disturbing.
A ClockWork Orange : Made by the kubrick ximself which instantly makes the film a household name. Although the book is way better imo they both deliver the same meaning. That not only are the Youths of this world bloodthirsty animals who without a seconds doubt would beat you for what your worth, not because you deserve it, but because you are weak. If you make that sadist incapable of inflicting violence, it will only make that person weak, and thus susceptible to the whims of other sadists that would, in a similar fashion, beat him for what hes worth. Its a viscous cycle that Western Society has grown ever more bewildered to the solution, even if the solution is quite clear and simple, that being to just beat them to submission by the state. Its a movie everyone needs to watch mostly since we've grown STUPID to how human beings truly operate and how thats disturbing i guess or something.
Midori (1992) : i dont want to talk about it because it made me sad but its about CSA and how children end up being exploited and groomed when they have nowhere to go, im not spoling it but pipol should watch it, its not that disturbing but it made me sad.
Man Behind the Sun: gore movie about Unit 731, disturbing because it happened in real life.
Threads: disturbing because its going to happen in real life
eraserhead and tetsuo the iron man can count as disturbing, they dont mean anything they just look cool