I sometimes like to add unnecessary parentheses or brackets to section things off and improve legibility, but I don't do any math stuff collaboratively, so I have no idea whether others would find that disruptive or helpful.

I mean, there are very few ambiguous cases when you know how the order of operations works.

Using parenthesis can really help if you want to simplify a term or need to rewrite something. I do that all the time because a lot of times you then can just cross stuff out fast on equations or get a common term that just has some factor instead of having a convolutet equation.

I got really angry because the prettier code formatter insists on removing parentheses, making things less clear. Because it's an "opinionated" formatter you can't tell it not to do that without using ugly hacks.

Sure, logically there are times when you don't need them. But, often it helps to explain what's happening in the code when you can use parentheses to group certain things. It helps in particular when you want to use "&&" and "||" to say "do X only if Y fails".

so it would be clearer

That's because it's already clear as is, as per the rules of Maths.

I think someone told me that order of operations is like a natural law

It's a natural consequence of the definitions of the operators. e.g. Multiplication is shorthand for repeated Addition - 2x3=2+2+2 - so if you don't do it before addition you end up with wrong answers. The order of operations rules is in fact just breaking everything down into Addition and Subtraction and then solving from there.

not a convention

There are some conventions, like left to right, but in that case that's only because students tend to make mistakes with signs when they don't go from left to right, so it's there to preserve teachers sanity.