Hi! I just got my Buds Pro 2 today, and after plugging them in to charge, I noticed a very loud coil whine coming from the case.
The noise changes depending on which charger I use, but generally AC-DC switching chargers produce a very loud, high-pitched noise, while DC-DC chargers (powerbank, laptop, etc) only produce a quiet clicking sound. Of course, I’m talking about the noise emitted from the buds case. The AC-DC chargers I’ve tried include some high-quality ones like Lenovo and HP laptop chargers. I’ve tried both with USB-C PD capable chargers, as well as regular USB-A 5V 1.5A chargers and the noise is roughly the same. No other devices connected to the chargers produce any sounds, and neither do the charger blocks themselves. I unfortunately do not have any GaN chargers to test with. Also, interestingly enough, the Raspberry Pi 15W USB-C charger doesn’t make the case emit any sound - charging almost completely quiet on that one, with occasional quiet ticking every few seconds.
The noise is independent of whether the case is open or not, and whether the buds are inside or outside.
I’ve also sometimes noticed noise coming from the case when it is charging the buds, but it itself is not plugged into any external sources of power.
The noise sometimes shifts in frequency (especially during the first minute of charging), but the noise peaks generally stay at around: 4031 Hz, 6000 Hz, 8062 Hz, 9750 Hz, 10125 Hz and 12188Hz.
Attached is a screenshot from Spectroid. Notice the lines at the right of the waterfall, as well as the huge peaks in the top graph. The long horizontal bit of noise at the bottom of the waterfall is a relay click of me turning on the power, and after a second the coil whine starts.

Any help would be greatly appreciated, as the noise is loud and can really bother me, even from the other side of the room. I’d like to post an actual audio recording, but unfortunately I couldn’t get it recorded well (in a way that could actually be noticed on the recording), so I guess I’m stuck posting Fourier transform and waterfall screenshots.