@frouke Going back to this earlier discussion, and as I'm catching up on it, I wonder if the atrophy could be due to lichen sclerosus (particularly, "differentiated"), with which I am especially familiar with lately.

It may not be, but in the interest of helping out with additional possibilities / information, I would only hope to help as you address this development.

I hope it is identified and managed to your comfort level. Best wishes.