Bumping noise Audi A3

[jas0n1]

Hello,
The car is 2020 Audi A3 1.5 TFSI with 28000km.
Recently, I have have mentioned strange noise from engine. I am dummy about cars, maybe it is normal. In a cold start there is not any noise. However, It starts when car warmed up and RPM is going below 1000. I cannot hear that noise from outside, only when the doors are closed inside.
You can hear some bumping noise in that video below. I have visited the service and the answer was that they did not hear such a noise before and I should not be worried about it. However, I am worried. Can you please have a look and let me know please.