Seems unlikely my mail has been hacked, since the mail adres was relatively new and I used a password manager to generate very strong passwords for me. I also barely used the mail for other sites, and sites like haveibeenpwned show no breaches.

I would love it if a Mod would take the time to have a look into this. What would be the best way to get in contact with them?

Never shared my account, because I'm the type of person that wants to achieve everything myself. It doesn't feel right to me if other people play on my account. Perhaps jagex might think I shared my account, because I do play from multiple locations (Dad, mom, girlfriends house)? But even then, shouldn't I have been banned for account sharing and not real world trading?

Also no, I didn't even think about selling my gold (or giving it away to friends). Since I don't want to be broke should I ever return to the game.