Reassigned with new schedule after break

Is it normal for your supervisor to suddenly reassign you to another group of students mid year? I have another para coworker who is dealing with my future new group of students as well. Do you think it is because I did anything particularly wrong or is it just for the students to not get too dependent or comfortable?

I was just told this today along with other feedback to be more careful with phones (I understand this one completely) and to circulate around the room more and be more discreet on the kids that you have so it cannot be seen that they are getting the extra help. I understand both but it is really hard when you have a really prompt-dependent issue where they do not listen at all so you have to get attention in more creative ways. It's really nuanced. I was told two people came to say this feedback and honestly I thought I was doing okay. Maybe not after all... It's breaking my heart to think I failed any of these kids or the teachers I work with. Does anyone have any information on this? Is it normal? I just feel like every action is so scrutinized and that I don't belong.