How these typically work is you had you’re steam guard compromised and swapped to another device. When thus happens you won’t get an email, notification, etc informing you so it’s easy to not notice. You’ll also stay signed into the steam app generating unusable codes.
You need to reset your steam guard, and change your password. You’ll most likely want to change passwords on anything that has the same info.
I’m sorry to tell you but steam will not help you recover stolen skins. Their lack of proper security with steam guard and refusal to take action is what keeps this scam market alive.
Yep most likely. I like using a password manager like bitwarden to randomly generate my passwords and have them all different. This way if one account is compromised you don’t have to worry about the rest. Best of luck.