Use a tool like Have I Been Pwned to see if your email has appeared in any recent breaches.

Once a tool identifies a working account, it is flagged as a "hit" and can be sold on underground forums or Telegram for a profit.

If a service notifies you of a breach, change your password to something unique and strong. Do not reuse this password on other sites.

The specific file you mentioned, "1,5M COMBOLIST GMAIL (TARGETED GAMING).txt," indicates a curated collection of 1.5 million Gmail accounts specifically gathered because of their association with gaming platforms (e.g., Steam, Epic Games, or PlayStation). What this file is used for

A is a text file containing massive lists of stolen credentials, typically in a username:password or email:password format. These files are used by cybercriminals to perform credential stuffing , an automated attack where they try these leaked pairs across various websites to gain unauthorized access.