Rumble of the engine at each switching

Hello, I’ve been driving a Corolla from 88 for a few months. Before that, it was the same model that I drove for 18 years – so I know the sounds… The “new” has a strange habit. The speed goes up to over 2500 after each shift, and then it falls down again. The normal idle speed is at 1000. I think it also consumes more fuel, right? The workshop did not find a Ursace and I had already settled with it. Now my wife with her Mazda has the same thing as Pfroblem. However, he was in the workshop because he always went out at the traffic light. Now he does the same as my Corolla, only turns higher on 3200 revolutions… What’s the matter with the cars??