Sounds like a SCAM setup. Do the following:

1. Scan for malware ... Your account is compromised.
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 clean computer.
5. Generate new backup codes for your Mobile App. https://steamhost.cn/twofactor/manage
6. Revoke the API key (there should be no key). https://steamhost.cn/steamcommunity_com/dev/apikey.

Początkowo opublikowane przez Kearo:

yesterday i voted on site though stem login & today i received this message did i make something mistake please help me to recover my account

There is an official support article about this scam.

Scam: Vote for My Team

The one account you are friends with is an obvious scam account. That is NOT a member of Steam / Valve support.

how can i report about that account by which i got scam ! and what i can do for my account ?

Początkowo opublikowane przez Kearo:

how can i report about that account

Every profile has a report button.

what will happen to my account now ?

i did all this steps to secure my account except last one not sure what to do about API key

1. Scan for malware ... Your account is compromised.
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 clean computer.
5. Generate new backup codes for your Mobile App. https://steamhost.cn/twofactor/manage

Początkowo opublikowane przez d3str0y3r:

Początkowo opublikowane przez Kearo:

how can i report about that account

Every profile has a report button.

got it i have reported about this account

Początkowo opublikowane przez Lilim:

Początkowo opublikowane przez Kearo:

yesterday i voted on site though stem login & today i received this message did i make something mistake please help me to recover my account

There is an official support article about this scam.

Scam: Vote for My Team

this is the exact scam happen with me !

Początkowo opublikowane przez Kearo:

what will happen to my account now ?

i did all this steps to secure my account except last one not sure what to do about API key

1. Scan for malware ... Your account is compromised.
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 clean computer.
5. Generate new backup codes for your Mobile App. https://steamhost.cn/twofactor/manage

The api key should be blank