Plastic rearview mirror button

My 2002 Buick Rendezvous has a plastic button on the inside of the windshield (yes I know the difference between plastic and glue or adhesive) where the rear view mirror used to be attached. I worked at GM for 25 yrs. (Moraine Assembly) and it was never GM policy to pay for a part and pay to have it installed if they didn’t think it needed or necessary. (the clear plastic button) Does anyone know what this button is for ? My dealer (Lang’s Chevrolet) says that there is a service recommendation that the windshield be replaced if the rear view mirror falls off, so he would not recommend that I try to scrape off the plastic button. GM’s rearview mirror adhesive kit, as well as the after market adhesive kits say that they will not adhere to plastic., and I can attest that they will not.
.What is an old geezer supposed to do?

I would call a local car glass shop and ask them. It would suck to have to replace the glass because of this.

Could it have been a radar detector mount?

Any reason you could not mount the mirror just below the plastic button or beside it?

If that glue won’t adhere to plastic maybe Krazy glue will. It’s no good on glass but maybe it works on plastic. Relocating the mirror sounds good too.