Get sunscreen off of mirror...?

How about amonia mixed with warm water? Or, my mom used to use warm water and vinegar to wash windows? Either is worth a try at this point.

Is it an acrylic or plastic mirror? It may have damaged the surface. If it’s glass, use an abrasive scrub pad and concentrated Dawn soap.

If the mirror is glass, try rubbing alcohol on the spots. Then polish the whole thing up with windex.

If you can actually feel the dots, try using a razor blade scraper to them. Then follow up with a cleaner.

Vinegar works great on glass. I’ve used it to remove tough mineral deposits.

An aside. Do you really want to spray stuff on your body that is this hard to remove?

I was thinking that too. It sounds like it would probably make a better adhesive than sunblock