The existence of two opposing PEPs says to me that there may be a case to be made for either side, so we should default to not changing things.
I used to think it’s likely that you can make a much stronger case for one side, but I personally feel that’s more for early language development phase. If it’s been a certain way for a long time, it ought to be overwhelmingly obvious and overwhelmingly supported by the community to change it. And even then I feel a bit of doubt.
If you're referring to this PEP's "twin", i.e. "PEP 758 – Allow except and except* expressions without parentheses", that is not an opposing PEP. These two PEPs are orthogonal. One does not contradict the other. They are twins only in the sense that they are both about exception handling syntax.
I used to think it’s likely that you can make a much stronger case for one side, but I personally feel that’s more for early language development phase. If it’s been a certain way for a long time, it ought to be overwhelmingly obvious and overwhelmingly supported by the community to change it. And even then I feel a bit of doubt.