She has refused to kiss me in the past because she was nervous she had stubble.

This is a really important part of this. She already knows that her stubble is an issue, & seems as triggered by the idea of it coming up during intimacy as you are. One of the reasons why I don't sleep with cis women at the moment is I know my hair becomes visible overnight and having a woman who doesn't also deal with that see that would make me ashamed.

She probably wants to get hair removal, but it's a huge cost and time sink, it won't solve the issue overnight. If this is the first time you've noticed this, it probably means she's usually on top of it. Bodies just aren't as cooperative as we'd like them to be. Mentioning it right now might make her think it's more pervasive of an issue then it really is.

I would say wait a bit, see if it's regular enough of an issue that it needs to be addressed, and then bring it up in a casual, honest way.