Clipping or stabbing you through a closed locker is a bug, but taking 100 damage when found in a locker probably isn't a bug as it was like that in previous versions too.
She doesn't teleport. I have done A LOT of experiments in various versions, this one included. She is just super fast (unbelievably so if you don't witness it like I have) when she spots you and you don't look her in the eyes. I should probably record my experiments and upload a video, it's amazing to see just how fast she is at times. That is why, instead of just running, you should look behind you every 3s or so when you are running from her in a straight line (where she can see you) as that will, probably contrary to what seems logical, often prevent her from actually reaching you. You will be surprised how little distance there can sometimes be between you and her when turning around to face her after 10 seconds in the middle of a chase. It can be a bit difficult to find the right balance between running from her and observing her while you walk backwards (no, let's call it moonwalk lol) away from her.
Can you show a video of her standing by the light switch without moving? That might actually be a bug (report it on discord if so), but she will likely move away after 60s as she has been programmed to only camp for that long. If she doesn't attack you, then how come you lose HP? Does she suddenly attack you when you are about to leave?
I don't think the game is unfair; you just need to know the "rules" and learn her behavior. Not gonna lie, it took me a while. There will presumably be an easy or practice mode again in the future, judging from the "Choose difficulty" menu.