Our pre-school teacher went full silent treatment to us when we had a friendly, respectful discussion with the administration about the teacher not addressing another student hitting our kid.

I'd be mindful of blowback to your kid in addressing this. I'm glad we addressed our issue, and we ended up moving our kid out early of that pre-school into a summer camp before kindergarten.

Depending upon the punishment/discipline, you may just want to move your kid elsewhere. I doubt the teacher will change.