Loss of Power in High Gears

Hello everyone.
I am a proud owner of a 2.0 TDI Touran, model year 2003, build date 04, with 136 horsepower.

I've owned the vehicle for 1.5 years and have driven 42,000 kilometers (or miles) during that time.
'I have very good power in the lower gears (1-3), but as soon as I shift into the higher gears (4-6) and press the accelerator, it feels very slow, even though the turbo is engaged at 2000 RPM.'
I'm not sure if it's just a matter of getting used to it, or if there's something more to it, but I don't feel the same level of resistance in the higher gears as I used to.
I have a diagnostic tool, and the error memory is empty.
With my device (not a VAG-COM), you can also access the control module and change other settings.
Where else can I look, and what values should I pay attention to?

Best regards,
Nihat