Why is this specific filename dangerous? Because it is predictable.
They are specifically designed for situations where you lose your phone, travel to an area with no service, or have a broken authentication device. Why the Default Name Matters backup-codes-username.txt
I notice you're asking for a paper (likely meaning a document or explanation) for a filename: "backup-codes-username.txt" Why is this specific filename dangerous
The file Backup-codes-[username].txt is the default name Google and other platforms use when you download your two-factor authentication (2FA) recovery codes. backup-codes-username.txt
Imagine you just locked yourself out of your house, and your phone—the only thing with the smart-lock app—is sitting on the kitchen counter inside. You are stuck.
If you download the .txt file to print it, delete the digital copy immediately after printing.