PC How legit is G2A?

I used to buy games and DLC packs on G2A. All of my keys worked of course.
However I stopped using it when the developers of the game "APB Reloaded" decided to ban everybody who got a key off G2A because supposedly there was a massive chargeback on those keys. However, that massive ban wave happened a year after purchasing the key off G2A.

Long story short, I got banned off a game because I bought it off G2A. Haven't used it since.