Even just as text, they can easily take your name and spread rumours speaking as if they were you.
Even just as text, you can get dog-piled: we evolved to be social creatures, and for groups of 150-200; for most of us, if we're called names by that many people in quick succession, it breaks us. That's a small online mob, as these things go.
But bullies these days also have effectively zero marginal cost cameras, so they can take as much video as it takes waiting for you to mess up, then do a Cardinal Richelieu — "If you give me six lines written by the hand of the most honest of men, I will find something in them which will hang him."
In my day, you could take up to about 24 pictures quickly before needing to take the film out and put new film in, and that would take a while to develop and actually cost money, so that just didn't happen (that I've heard of).
But it's not just taking photos of things that actually happened and misrepresenting them, even one picture is enough to put your classmates into AI generated porn… which is, as you may expect, a thing that kids these days are getting into trouble for doing. In my day, such image manipulation was manual and expensive* and therefore reserved for celebrities, though I doubt that's any real relief to Sarah Michelle Gellar in one example I remember, nor to GWB and (today the relatives of) bin Laden in the other.
* we had a single copy of Photoshop… donated to the art department, which had only one (old) Mac on which to run it. Hard to pirate that kind of software back then even if you knew how to use it, definitely couldn't get unsupervised access to that machine.
But it's not just still images these days, a brief audio recording of your voice and that can also be synthesised. Dictaphones were just starting to get affordable in my last year of mandatory education, and we pranked a teacher by mixing their last lesson with new age relaxation music, burning a CD of that, printed a cover saying something about curing insomnia, and giving it to them as a "last day gift". Now everyone has a dictaphone in their pocket, now you can synthesise anyone's voice saying anything, make images of them appearing to do anything. And a world where those things are, for now, still often treated as if they were real.
But even just text, the internet made it a different world than when I was at school. The psychological impact of being told you, personally, are Officially Bad, that's something that sticks with us and hurts us even when it comes from a pattern of illuminated pixels on their Mandatory Rectangular Communication Prism caused by someone on the other side of the planet who had no business talking to us in the first place; and that distant person can be incited to form part of a mob by a pattern of illuminated pixels on their Mandatory Rectangular Communication Prism.