I think we might have the same problem.
I just took delivery of a 23 MYLR7 yesterday (3/13) and then drove home about 250 miles. At some point I realized it was a noisier than the 2021 Model 3 SR+ that I had before and thought, maybe this is normal now that there is a front motor. My Model 3 was dead silent.
Once I got out of traffic and out on flat, open highway, I was able to investigate a bit further: HVAC system on/off, different speeds, etc. The conclusion for me is that it comes on around 50-55 mph and continues up to 75. It is only really present at steady-state conditions, not accel or decel. (There are different, "normal" sounding noises during accel and decel, as I expect.) It is a relatively faint noise that can be drowned out somewhat with the sound system, but once you hear it, it's hard to ignore.
Sidenote: I'm a controls/test engineer for commercial vehicle powertrains, so I basically get paid to find and fix problems like this... there may be people that would never even notice this noise. But I think I have an above-average sensitivity to noise and irregularities in data.
The OP described it as a sound that sometimes "sputters". That's the same impression I had. It is like a staticky noise coming on and off in a somewhat irregular pattern, which is probably what makes it so annoying. At one point I thought it might be related to a coolant pump or valve based on the sound.
I was searching facebook groups and forums like crazy when I got home, trying to see if it was only me, and it seems like there is somewhat of a history here. I'm not sure all cases are the same issue, but there is definitely some kind of trend. Possible root causes I've seen discussed are: ground straps, penthouse perimeter seals, bearings, drive units, windshield seals....
Needless to say, I'm a bit disappointed right now. Brand new car, and an issue that I have no idea if Tesla is really going to help fix or not. Besides this, the car seems to perform great. I'm going to start with a service center appt.