It's a game ban, and bans are issued with a time delay.
The game ban is permanent and cannot be removed.

If someone actually accesses your account:
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://psteamproxy.yuanyoumao.com/twofactor/manage
4. Change passwords from a trusted/clean device.
5. Generate new backup codes for your Mobile App https://psteamproxy.yuanyoumao.com/twofactor/manage
6. Revoke the API key https://psteamcommunity.yuanyoumao.com/dev/apikey (there should be nothing in the APIKEY)

Oh yeah, if that's just a made-up excuse, I can tell you right away that it won't work.
The account in question will always be punished, regardless of who violated the rules with that account.