Hello friend, the same thing happened to me once but I was able to stop it. Now things are a little complicated so to speak, when you accept unknown friends "you practically give access in a certain way to share your data with them." Do not accept any friend unless they are trustworthy, the theft method through Steam Guard is that you have to set it so that for all access you need prior permission from your fingerprint or stop, this way it becomes more difficult for them to hack your account. It is also possible if you have money or valuables it works since it is necessary to have prior permission from you or your cell phone. Remember that when they hack they can also be on your cell phone so be careful with that.
Remember that pirated apps make it easier to steal things.

They tried to steal my Steam account and they almost succeeded. They also did what happened to you. They wrote insults and things like that, but since I'm from another country, my friends didn't understand what I sent unless they used Claro translator.

What they did steal was my Discord account. I couldn't recover it. They did the same thing: offensive messages and misleading advertising to steal things.

With Steam, luckily I didn't have any balance XD, so they only got a few cents from me. "They made a purchase of an item through the store" worth $0.10 XD. Anyway, they tried to steal valuable items from me, but it was all through fingerprint verification, so they couldn't.

Delete friends you don't know so you're left with only 20, even the old ones who haven't been online on Steam for 1 to 9 years. Setting your account to private also helps.

引用自 SteveCall：

Hello friend, the same thing happened to me once but I was able to stop it. Now things are a little complicated so to speak, when you accept unknown friends "you practically give access in a certain way to share your data with them." Do not accept any friend unless they are trustworthy, the theft method through Steam Guard is that you have to set it so that for all access you need prior permission from your fingerprint or stop, this way it becomes more difficult for them to hack your account. It is also possible if you have money or valuables it works since it is necessary to have prior permission from you or your cell phone. Remember that when they hack they can also be on your cell phone so be careful with that.
Remember that pirated apps make it easier to steal things.

They tried to steal my Steam account and they almost succeeded. They also did what happened to you. They wrote insults and things like that, but since I'm from another country, my friends didn't understand what I sent unless they used Claro translator.

What they did steal was my Discord account. I couldn't recover it. They did the same thing: offensive messages and misleading advertising to steal things.

With Steam, luckily I didn't have any balance XD, so they only got a few cents from me. "They made a purchase of an item through the store" worth $0.10 XD. Anyway, they tried to steal valuable items from me, but it was all through fingerprint verification, so they couldn't.

Delete friends you don't know so you're left with only 20, even the old ones who haven't been online on Steam for 1 to 9 years. Setting your account to private also helps.

Yeah, that’s fair. Looking back, I did log into a third-party site (Rustly) without realizing it was basically a phishing setup. At the time I thought it was harmless, but in reality I just gave away my own keys.

Steam Guard was enabled, but like you said, it can’t protect you if you hand over the codes yourself. Hard lesson learned — one bad decision cost me my Rust account, 800+ hours, and 50+ skins. Definitely won’t make that mistake again.