NITEO 18V Cordless Screwdriver: Sparking During Sudden Speed Changes - Normal or Issue?

In a drilling machine during a sudden increase in speed (stepwise) such as when switching quickly from zero to max, or a fast jump from low to high, there are flashes - is it normal or is it not good enough to give rise to a complaint? This is the NITEO 18V budget.

I give the picture as an attachment to illustrate everything - everything happens at the rear ventilation openings - where the moving parts are visible during work.
The biggest flashes arise as if from a quick rotation the finger is removed from the switch and the drill stops instantly from high revs to zero.

Not normal
The cause may be spent brushes in the engine or one of them.
Working further with sparks you can damage the engine commutator. or this has already happened

Sparking when stopping is quite normal. That's how the brake works.

It's completely normal. So when starting and braking, the current is very high. During rapid starts even 10 times higher than in normal work; when braking, the engine is simply shorted, and the accelerator works like a generator so it's no wonder it sparks.

The equipment is new - the consumption is off.
In summary, it sparkles in 3 situations.

1. How slowly and smoothly I increase the speed, it is okay until I reach the end of the switch - then there is a sudden spins of rotation and is accompanied by a flash, plus a really microscopic continuous sparking, at continuous operation at the highest speed.
2. A very large flash is instantly activated at the highest speed when switched on
3. The same at stop (via switch) from the highest speed to zero.

So, now it's only to determine if it's possible to live with it or a complaint, because maybe these budgets do that such flashes are normal

Edit: Ok, it also looks like it's okay - if I do, I will not go back to the seller of the butt and make problems

I have an AEG screwdriver, which cost 4 digits. And also sparks. If you work with it a little and the brushes will settle well on the commutator, the spark will decrease, but it will not disappear completely. At the Technical University of Lodz, in a machine with a large engine, a brake was also installed (counter-current braking). Because this is a health and safety requirement. Believe me, the machine hall is light as if someone stopped the machine with a safety mushroom.