Thank goodness it's not just me. I just got a 2022 LC500 convertible. The ML system is really disappointing. I've tried almost all reasonable combinations of neutral tone, boost/cut across combinations of treble/mid/bass, fader front/back, surround on/off, auto adapt on/off, etc. and can't find even a passable blend. It also seems to vary depending on the source material - some of it sounds OK, but much of it sounds very tinny, with minimal mid-range, and biased to the center dash speaker.
I've owned a large number of cars (I'm old), some with aftermarket radios, some with default OEM, and some with "premium" OEM radios. My 2019 RDX with the ELS Studio premium OEM sounds infinitely better than this with minimal adjustment from defaults. My old 2009 Honda Fit (!) sounded better than this.
I haven't been back to the dealership yet, but I do intend to complain when I do go. Maybe if Lexus gets enough continued blowback, they'll try to do something about it. Given how some members here seem to have a better sound experience with their cars, I have to wonder if there are defective amps or head units in the field that some of us are burdened with. Of all the YouTube reviews of the car that I saw, I don't recall anyone complaining about the audio - they usually just praised the exhaust note and whined about the trackpad - maybe they never turned the radio on...
I did see where someone in a UK Lexus group had changed out the default amp with an aftermarket unit with adjustable DSP so he at least has a chance of balancing the audio. He had a source there that built a custom harness adaptor, so no wire-cutting/tapping involved.
I intend to feed some white and pink noise through the unit to see what it looks like with a spectrum analyzer. I don't expect a very flat response curve.