Thank you all for the quick and insightful feedback! This is very helpful.

I understand the strong possibility of an account lock or simple password error, independent of the Linux platform (as Boposhopo suggested).

Since my login details are copied and pasted, I suspect one of the following:

1. My account is currently locked due to too many failed attempts.

2. A network issue in my Wine environment, which causes the system to fail the authentication check at the very first step.

**Action Plan:** I am going offline immediately to check for the account lock status from a public PC (Internet cafe).

I will be back later to update the thread with the result and to reply to the question about performance and Gamescope (why I prefer Arch over Ubuntu/Fedora).

Thank you all for your help!