netflix changed my plan without permission??

i currently have a netflix subscription for the first time ever (like two months now), so i’m not very experienced with this service yet. the only reason i subscribed is bc a friend wanted me to watch his favorite show with him, and i don’t really use the subscription for anything else (as in; i pretty much dont watch any other show or movies on netflix), due to this i chose the cheapest plan because i really don’t need more. however i just now (a few minutes ago) got a notification from my paypal app that netflix charged me 20€ for the premium plan instead when i definitely did not choose that plan. what happened here? did i get hacked? or is this something netflix just does??? can anyone help/give advice what to do here?