Hackers use Google Dorks to find these open doors.
: These files are often "combo lists" or "logs" harvested by hackers using info-stealing malware. Accessing or using this data is often illegal and unethical.
Notice that none of these rely on finding an index of gmailpassword.txt file.
Manage Your Passwords Safely & Easily - Google Password Manager
Change your passwords regularly and consider using a password manager to generate complex, unique passwords.
If you are looking for your own lost information, you should use official channels rather than "dorking" for leaked files:
: These links often lead to malicious sites designed to look like a leaked database. When you click, they may attempt to install malware or spyware on your device to steal your actual credentials.