That is highly illegal tbh I’d call the police

Set up cameras (needs long batteries or motion sensors) if you are able to catch them in the act report it to your local police for 1. Vandalism 2. Defacing Private property

I’d say it’s normal because it’s like playing with your hair. If it’s just on a toilet or something I’d say it wouldn’t be normal if you do it in public or go out of your way to do it too much.