In rap slang, "tweaking" means on drugs, or in this case, Lil Nas X meant "he must be on drugs". According to Urban Dictionary “tweakin” is described as the act of not making sense of anything ...

They defined the slang term as having a similar meaning to cringe, which the Gen Alpha expert deemed was in. Fam Liv Kaplan asked her little sister Brooklyn about slang terms that are in and out.