What is MAC

So basicly, on every Server i found exploits until now i have been banned right after executing ExploitCity by "[MAC]" for executing Invalid lua.. On a few other server it happend too where no exploits were existent.. Anyway, what is MAC and how to bypass it? Im usin an CAC bypass already but this MAC is gettin in my way

Modern Anti Cheat if you can even call it that.
Simple to bypass.

How to bypass it?

If it is so simple to bypass would you mind helpin me out? After almost an hour of googlin around i did not find a single bypass..