Once you send the file, they extract your login cookie. This allows them to bypass two-factor authentication (2FA) and log into your account instantly. How to Stay Safe Cookie logging explained - Developer Forum | Roblox

They send a video tutorial showing you how to go into your browser’s developer tools, click the Network tab, and "Save as HAR" .

In the context of Roblox, a (HTTP Archive) is a log of a web browser's activity used primarily for troubleshooting network issues. However, it is also central to a dangerous account theft scam because it contains your account's session cookies , including your ".ROBLOSECURITY" token . The Roblox .HAR Scam