I have a 2019 model "Exclusive"
I also have a terrible and high frequency (hochfrequent) noise (störendes gërausch) coming from my fan/blower/ventilator.
No noise when running on ventilator speed 1-3, very audible/hörbar when running on speeds 4-6 and noise is gone when running on full speed (I guess then blower noise is higher).
As car is still under warranty I delivered it to Opel dealer and asked them to check it out.
They replaced the fan/blower - but the noise is still there.
They suggest to dismount entire dashboard to see if they find where noise is coming from
If any of you members have experienced the same problem (and, perhaps have a solution for it) - please add your comments here.