Whistling after timing belt replacement

Hello everyone.
I picked up my Golf Variant with the ALH engine from the dealer today.
The timing belt, including the water pump, has been replaced.
Now, at approximately 1800 RPM, I'm hearing a faint, short whistling sound (or something similar) coming from the direction of the turbocharger.
(Whether during acceleration or when releasing the gas pedal)

Does anyone have any idea what this might be?
Could it be that the timing belt is not 100% correctly tensioned, but only 99%, and that it builds up so much vibration for a short time that it comes into contact with the cover?
Unfortunately, I haven't been able to perform any measurements yet because the cable I ordered has not arrived yet. (@Rainer: The money was transferred online today ).
Could it possibly be related to the turbocharger? Because it wasn't happening yesterday, but only now, after the timing belt replacement. (Although you don't have to touch the turbocharger when replacing the timing belt.)
Please provide your opinions.
Thank you.

Is this your first timing belt replacement? I think it's just the "break-in noise" of the new belt. It sounds a bit like "singing," but it should go away after a few days.

Regards,
Peter.

Hi Corradoman,

Take a look at the timing belt tensioner. In the center, on the rotating part, there's a small protrusion, and a little further out, there's a small recess. Both the protrusion and the recess are about 1.5mm wide.
They should be positioned relatively opposite each other. If they are not (more than 2-3mm apart), the belt tension will not be correct.
"Too tight timing belts 'whine'."

Best regards, Rainer.

Although it wasn't my first timing belt replacement, it was the first one I had done on a TDI at a VW dealership.
With my Pirelli back then, or with my Corrado, which I worked on myself, the "background noise" was probably always a bit higher, so I couldn't really hear the "singing" (of the turbo). This time, I had it done professionally because of the pump settings, etc.

Thank you for the answer, it helps me sleep better.

Rainer K. wrote:

Hi Corradoman, Take a look at the timing belt tensioner. In the center of the rotating part, there's a small protrusion, and a little further out, there's a small recess. Both the protrusion and the recess are about 1.5mm wide. They should be roughly aligned. If they are not (more than 2-3mm apart), the belt tension will not be correct. "Too tight timing belts 'whine'." Greetings, Rainer

Hmm.......
Actually, VW should be able to handle this, but thank you; I'll check it out.