Fan working on reduced speed is a swarm of mosquitoes  

Fan working on reduced speed is a swarm of mosquitoes

Hello everyone!
I experienced many weird noise-related things with my fresh Prusa MK3, but this one is cool enough to have it's own thread.
Preamble: when I print PLA, I can bear the noise levels prom the printer in Silent mode. When I print PETG, I have to carry the printer to the basement, because of loud noise somewhere at 2.5kHz, emitted by the print fan. It happens only when fan speed is lower than 100% (so PWM is involved), and reduced speed is always louder than full speed.
Just listen to the videos:
Idle: https://1drv.ms/v/s!ApPvcW5jKQg0gYZZYeQLQPiahCZiCQ
During print: https://1drv.ms/v/s!ApPvcW5jKQg0gYZXYr-J4GVFu7VaGg
I don't have external mic, so can use only phone's mic, which is directional and pretty good in noise cancellation. But I think it's enough to get the picture, especially on second video.
Do you have same terrible noise under 100% of print fan speed?

Update: I am on 3.5.1. @vintagepc suggested to update to 3.5.2 or 3.6.0 - will do it and update (or, hopefully, delete) the thread.