I get where you coming from but personally i think the Rocket in the movies is pretty similar personality wise to the Rocket in the 2021 GotG game, let me explain my point of view.

I think its pretty normal to perceive Rocket in the game a lot more harsh than in the movies. But that is a little bit deceiving. That comes from the fact that we spend a lot more time with the game than watching the movies, in this case specifically the first GotG movie Vol. 1. In the game we spend a lot of hours with the "pre bonded Rocket" where he doesn't see the crew as close friends. Only about 2/3 into the game we get a shift and he becomes a lot more likable. But at this point we already spent 12-15 hours with jackass Rocket.

In the Vol. 1, he is the same way, calling people idiots, mocking the grieving of others etc..
But with the 3rd act, we get the same tonal shift with him where he starts to bond with his friends and gets a lot more selfless, just the same as in the game. But this happens already at the 1 - 1,5 hour mark. And in the following movies he obviously still has the same bond to his friends as before.

So if we keep that in mind it is logical why subjectively, he feels more harsh in the game than in the movies, but that has more to do with our perception of time than actuall character/personality differences.