If you suspect you've already interacted with a file like this, I can tell you exactly: to secure your account. How to scan for malware specifically targeting Steam.

The download may contain malware, spyware, or ransomware that can infect your PC [1].

Only use the official Steam website or the official Steam Client.

Never download or open suspicious .txt files from unknown sources, Discord links, or unsolicited emails [1].

Ensure Steam Guard (2FA) is activated on your account to prevent unauthorized access [1].

It may prompt you to enter your credentials on a fake site, harvesting your information. How to Stay Safe

Disclaimer: This information is provided based on the general context of such file requests online. Engaging with suspicious files carries inherent risks.