constant whistle sound when driving

I recently started hearing this whistle noise, the pitch of the whistle is linked to the wheel/MG2 speed.
It's only audible when I'm pressing the gas pedal (so when MG2 is delivering power)
When I'm coasting or in neutral everything sounds normal.
It's very loud at high speeds above 100kmh (60mph) but it's also audible at lower speeds.

I'm thinking that either the transaxle has a bad bearing,
or something around the transaxle got displaced and is now bridging an existing frequency from the eCVT to the rest of the car and amplifying the sound somehow.
The weird thing is that the car still drives perfectly and there are no fault codes.

Already changed the trans fluid, but that didn't help. wheel bearings also seem fine.
It's also not an air whistle, since the sound stops as soon as I release the gas pedal.

I took it to the Toyota dealer but they said they didn't hear anything abnormal during the test drive, but I suspect they didn't check it very well (they don't have a highway nearby, so they might have only checked 100kmh for a couple of seconds.

Hope that anyone here has any ideas, love this car so much, but ever since the sound started it's not very pleasant to drive it at highway speeds.

It's a 2007 Prius with 220k km / 136k miles

 

Yes, i tested on a regular OBD2 scanner as well as Techstream. Actually recorded this whole live data stream and paired it with a stereo recording under the hood while driving. (mic is facing backwards, so Left is engine side and Right is transmission side).
With this vid I was able to conclude that the noise wasn't related to the speed of the ICE, but was directly linked to the vehicle speed and MG2 speed:

 

Could be maybe, it really seems to come from the side of the transmission though..

 

I also did a test when revving on jack stands, the sound also seems to be there then.
made a 30 sec compilation video of all the relevant footage i gathered so far:
1. sound from the cabin
2. sound when revving on jack stands
3. sound recorded from engine bay (techstream data on screen)