My ultra has no high pitched sound, so I'm only speculating from the various recordings I've heard.
But it sounds more like power supply whine than fan squeal to me. In the recordings I hear a more pure sinewave-like sound that could be a sub-harmonic of the switching rate. I've also heard it chirp a little, which again seems more like a power supply issue. It could be from a coil (usually) or a capacitor (not as likely when new). Changing the fan speed could still effect the volume. You may recall the 2018 Mac Mini (I believe that was the model) had quite a problem with coil whine initially.
It would be tell-tale to know if the volume or pitch of the sound changed with the load put on the power supply since the fan speed virtually never changes under load. That should be tested by both running the CPU/GPU harder and also by exercising the SSD with a somewhat sustained speed test or something similar. If you hear the high-pitched sound change in either situation it's almost certainly coming from a power supply component.
Yes this is definitely coil whine and I hope people going forward are specific about the fan noise vs. this because coil whine is a LOT more annoying in a silent environment. Coil whine from a $5,000+ computer is very unacceptable.
It's concerning someone mentioned their Studio developed this after a week or so because I've never heard of that happening - either it's present from the start or it isn't (until maybe many many years down the road when a component starts to fail). If it's ran hard for a week and stars appearing there's a manufacturing defect in this product, IMO.
I have a fully-specc'd out Studio slated for delivery in about a month and this is very concerning... given the long lead times I'll probably try to take it anyway and just return it if it has the problem but I will stress-test the hell out of it to burn-in the components and make sure, coil whine is an absolute deal breaker for me. I will probably fall back to using a hackintosh until the Mac Pro comes out if that's the case but I need thunderbolt for audio interface(s) and ~5TB of SSD space and so I'm holding-off on buying a pci-e RAID card and m.2 drives until I know one way or the other... a lot of the software I use is annoyingly picky about being on external drives, even if they're fast.
The two power supplies being vastly different is also very odd, unless they are specific to the Max / Ultra. That much variation does suggest a revision, if the CPU is not the differentiating factor.
edit:
Ramping down the fans to 1100rpm and then running 3D rendering tests (or gaming) should max out the CPU / GPU and provide some variation as to what's being drawn on the screen. This will demonstrate coil whine effectively because the Fan Noise won't mask it. Changing fan speed will have no effect on Coil whine unless it's heat-related which wouldn't become apparent until you have the thing fully-loaded for quite a while. Changing the viewport quality / camera direction in a 3d rendering app, or your POV in a game from a stressful scene to a less stressful one graphically will make it apparent because you'll hear a slight variation in the pitch of the whine - more stressful power consumption tends to produce a 'pulsating whine' like the chirping heard in one of those clips.
Some recent SSDs have also been somewhat poorly manufactured and produce this same type of whine when heavy disk I/O is going on so it might be worth testing that also, or in tandem with a fully-loaded cpu/gpu/possibly vieo encoders.
There's no excuse for this thing making coil whine noise like that unless someone really messed-up somewhere in the design phase, or one of their suppliers is producing garbage that QC isn't catching. Their engineering staff has to be testing these at home or in a very quiet room and should have picked-up on it.
