You will have to show me the coaching manual where it says the last man should give way to an attacker who is about to enter the penalty area and face a 1-on-1 with the keeper. Ampadu's only option to close down the player outside the box required fast acceleration, and at that speed he had to commit to playing the ball. What else is he supposed to do, choose a different line with the associated risk of making a tackle inside the penalty area? I think we would all be happy if he made that tackle against Scotland or Ukraine with 8 minutes to go.
About the acceleration, I don't know where it came from either and it seems like a new thing to me. Maybe it's the Italian coaching?