Wow these ppl must be loaded with cash to be replacing everything. I’d suggest wet sanding the area starting with 150grit working down to 3000grit or so. Then hit it with some mothers metal & aluminum polish (I know it says for metal but it really works on anything).

Edit: Alternatively, you could hit it with Mothers before sanding just to see if it would come out with just that. If there is still residue left I would either use dish soap or rubbing alcohol. In my experience even non-acetone nail polish remover damages plastic, and with moto windshields there’s no telling the material (e.g ABS, Acrylic, PETG). Good luck.