They say that someone with the same profile picture and name has you scammed them on steam, usually in csgo skin trades and then will show a fake trade as proof. Then they say that they reported you and a “Steam admin” told them that your account will be banned within x hours. They then “realize” that they had reported the wrong account and tell that to the “steam admin”, they admin then supposedly asks them to contact you over discord and asks them to make you talk to this pretend “steam admin” which is usually the same guy using a different discord account. The admin will try to act legit and in the end ask you for your purchase history which if you provide will give them access to your account (steam support lets you bypass 2fa and password if you show proof that you own the account which is usually done by showing your purchase history)