Sounds like one of the two fans is bad/going bad to me. which is awful sounding in your case. alot of people complain about the power supply being noisy but thats just crazy bad lol
The outer one is pretty easy to get to, the other one isnt too bad either, but not as easy.
I think they are different sizes, so that makes it kind of annoying.
If youd like there is a thread on the power supply’s fans (being noisy in general) with all kinds of people’s solutions, from a swap out to re-engineering it and everything in between
actually theres lot of them, here are a couple
SM2 power module noise - Snapmaker 2.0 - Snapmaker: where creation happens