I bought the car used and I just found these two “abnormalities” in the rear glass. Not sure whether these are common wear and tear things or the beginning of an expensive problem.

It's been mentioned in the C238 forum. Options are a new top or finding a convertible specialist to repair. Also, keep an eye out for fraying on the cords of the top mechanism.

Thank you. I found the post you’re referring to. Seems to be a common problem with newer convertibles.