You're not banned, but your account has been compromised.
Someone is trying to scam you.
The message on your profile comes from the scammer who has access to your account.
Follow the steps to secure your account and don't trade items.

Follow ALL these Steps to secure your account:
1. Scan for malware https://www.malwarebytes.com/
2. Check that the email and phone number on the Steam account are still yours.
3. Deauthorize all other devices https://steamhost.cn/twofactor/manage
4. Change passwords from a trusted/clean device.
5. Generate new backup codes for your Mobile App https://steamhost.cn/twofactor/manage
6. Revoke the API key https://steamhost.cn/steamcommunity_com/dev/apikey (there should be nothing in the APIKEY)

Это не вак бан, а мошенники получили доступ к аккаунту на фишинговом сайте. Если передать кому то вещи то они уйдут злоумышленникам.
Нужно выйти на всех устройствах и сменить пароли