I used to chew on stuff in school until 4th grade at least. I don't think that by itself is alarming. It's the whole package.
I will say that although a teacher may seem toxic to us, the child may be largely unaware of that.
From what I've read, it doesn't sound like she needs to be pulled out of school immediately. If she has to be away from her parents throughout the school day, it might as well be in a relatively stimulating environment with peers to socialize with. I would try for whatever accommodations are available, even just letting her quietly read or stretch in a corner when she's done with her work. Maybe she could have a fruit gummy snack for times when she needs oral stimulation.
Speaking of oral stimulation / sneaking, I just remembered something I did with my kid. I sent gummy vitamins to school with her, and she was allowed to have those when she felt the need to eat something. Whether that was the reason she stopped taking the teacher's candy stash, I can't really say, but it's a thought. https://www.amazon.c...TTDY0H1J75&th=1