Car Jerking/Hesitating When Accelerating/Starting

"Recently, I've been having a problem with my VW Golf (ASZ)."
When starting, the engine speed fluctuates between 1000-2000 RPM. When applying light, constant pressure to the accelerator, it jerks violently, and a grinding noise is produced, like something is slipping or making contact irregularly.
It's gone above 2000 RPM.
If the engine power is simply increased (e.g., without other modifications), the grinding noise becomes even more pronounced.
Also, the noise is also worse when the car is fully loaded.
During this process, noises occur that sound like an irregularity or something rubbing.
The sound can only be heard from the inside, not from the outside, and it doesn't always occur, regardless of the temperature.

-The wheels rotate freely without any friction.
-The drive shafts also don't rub against anything.
- The exhaust is also stuck.
- No performance loss detected (performance test).
-Error memory cleared.

One might think it's coming from the transmission side.

Could that noise be coming from the flywheel?