SS executors work by inserting a gui insert model in the game that can run things in serverside because it is compiled on the server. Not much of a bypass, but a welcome one to be sure.
Mainly just wants money and disguises as free
FE was added by ROBLOX in 2017-ish to prevent a client like you to modify server-based values to prevent stuff like this happening to your screen. https://www.youtube.com/watch?v=1QUXkCOWmng
Some exploits may or may not need hats. The GUI may not actually list any hats to use, so you just assume it's fine. These hats however are important to make those serverside scripts you use like for example the hand that displays above your character.
So most (if not ALL) games have FE enabled to deter exploiting. It's just roblox's brand of Windows Antivirus.
If you use a VR hack and run it on clientside, it has a chance of breaking you and making you absolutely invisible to anyone else and you can't move.