My PC may be compromised after running a suspicious PowerShell command

That command bypasses PowerShell’s execution restrictions, downloads a script, and runs it immediately. Scripts like this can replace legitimate executables, alter permissions, and hide changes, so the Steam errors may just be a symptom rather than the main problem. Don’t keep using the computer for sensitive activity while investigating it.

Assume the machine is fully compromised, potentially including remote-access malware. Disconnect it from the internet and use a different, trusted device to change your email, Steam, banking, and other important passwords. Revoke active sessions, enable two-factor authentication, and contact Steam Support if the account itself was accessed.

A normal reset or upgrading from Windows 10 to Windows 11 may not be enough. The safest approach is to back up only irreplaceable personal files—carefully avoiding programs and suspicious scripts—then completely wipe the system drive and perform a clean Windows installation from official installation media. Make sure the installer is created on a trusted computer if possible.

If you can’t reinstall Windows yourself, shut the computer down and take it to a reputable technician. After the clean installation, fully update Windows, reinstall applications only from official sources, scan your backed-up files before copying them back, and monitor your accounts for unfamiliar logins or purchases.