I would write a parent letter of concern.
Dear School-
What I see at home is my child, XX, will get overstimulated where behaviors get bad when she's allowed to use electronics. I'm not sure that allowing her to use her Chromebook during 'brain breaks' at school does the same thing. I do feel that allowing her to use her Chromebook at school for " non essential academic tasks", as stated in her IEP, does not follow her IEP. I would rather see her looking at a book, playing cards, playing with a fidget, punching a punching bag or other heavy physical activities rather than allowing her to use electronics would work better to reset her ability to stay on task when she returns to the classroom after taking a break.
Can we try these activities and see if they work better than having her on her Chromebook?
Thanks,