I hate to say this but you may not have much choice in the matter if you want to keep your job.
Changing teachers' grade levels is a tactic for new principals to exert control. They want to show that they have the power to do anything they want in their new school. Teachers who are entrenched in their grade levels are very powerful because they know what works and doesn't work, they know the history of the school, and they are usually the leaders in a building. Changing grade levels shakes up the staff and makes them more pliable. Principals believe those teachers will be forced to reinvent themselves, which is not necessarily a bad thing. This is one of those things they learned along the way when they were getting their administrative credential. If they are new principals, they often have mentors who advise them to shake it up.
Moving teachers is also a ploy to get rid of the teachers they do not like, either because they are "old school" or because of personality clashes, or simply because they have been told by the superintendent to get rid of "dead wood" (expensive teachers who have been there for years). In my district one superintendent told all the principals that they had to get rid of at least one expensive teacher per year. A principal from my school was lauded as the "top rookie principal" because she got rid of not one, not two, but three "dead wood" teachers in her first year. The teachers she got rid of were 25-year veterans, and incredibly strong teachers. They were much-loved by the staff, students and community.
Any complaints will be seen as insubordination and those teachers can then be written up. The teachers either transfer if they can or get early retirement if they can, or are fired after a failure to thrive in their new grade level.
I have seen this policy more times than I can count, and those principals do not understand that they leave chaos and disaster in their path, especially in a low-income school.
I wish you the best.