Report, block, enjoy the rest of your day.
Valve doesn't use chat messages(or other platforms like Discord) to communicate important things like this.

引用自 silveryulia：

Am I getting scamed?

I received a message from someone that my account will be banned. He says that I am flagged as a scammer/has fraud items. But I don't know anything about it and cannot find anything. He is asking me to sent a friend requist to Amy Baisch who should be a reviewer.

I have also made a support ticket, but maybe someone has had this before?

Yes, it's a scam.

There is even a support article about this scam.

Scam: I Have Been Reported and Will Be Banned

this is sometimes the middle of the scam,

just to be safe

do no trade until you have done these

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)

引用自 Lilim：

引用自 silveryulia：

Am I getting scamed?

I received a message from someone that my account will be banned. He says that I am flagged as a scammer/has fraud items. But I don't know anything about it and cannot find anything. He is asking me to sent a friend requist to Amy Baisch who should be a reviewer.

I have also made a support ticket, but maybe someone has had this before?

Yes, it's a scam.

There is even a support article about this scam.

Scam: I Have Been Reported and Will Be Banned

Thanks! I blocked him

OP, your very smart to ask on here. Good job not being the million of people on steam that get scammed.

Yes this does sound very much like a scam. Do not listen to it or do anything they tell you do and they should be blocked and reported.