Pollution Outer varnish

Hello together, I’ve been having weird brownish stains all over the car for a few months. Add pictures. I’ve already tried all sorts of removers (light grating, resin, beetles etc.) but they just don’t want to disappear. Maybe someone knows what that could be and what would help? With a lot of pressure you get them away to some extent but by that I probably scratch the paint and they are really everywhere .. that would take forever.