At DS1 school it is very hard to switch teachers unless there is another schedule change that forces a section/time change. There are multiple levels of approval needed. Clearly there is something going on here that should be addressed and the advisor can help…
I have heard about the switch to physics in 9th grade, and but didn’t think about the math to go with it - interesting. DS2 is taking physics in 9th grade, with the rest of his grade, definitely with plenty of math. Everyone at his (small day school) school is taking at least Algebra 2 in 9th grade (many are taking Pre-Calc and 2 are taking Calculus), so they are able to run a math-based physics class.