I had something similar happen to me almost 2 weeks ago. A friend of mine who i played Rocket League sent me a message to help him with a Rocket League tournament as his friend has too much ping.
I agreed to help because i didn’t think much of it as it was late, then he sent an ESL link to sign up, (which i shouldn’t have done) and lost my account and rocket league items.
But gladly steam support got my account back really quick after contacting them with proof that i own it, and got my Rocket League items back too by contacting Psyonix later on.
So yeah, moral of the story, from now on i’m double checking links even from friends that i know.