Yeah, he’s kinda just two-dimensional evil guy in The Clone Wars. They don’t really talk about his past or who his is or what his motivations are. They do have a couple episodes where they show Serenno for a bit (which is where his title is from), but that’s as far as it goes.
If anything, I’d say the AOTC version is more nuanced and intriguing. In The Clone Wars, he’s just about straight up evil Sith Lord.