Wow... this makes me wonder if something is wrong with mine (Rheem installed in March 2021). I just used an app on my iPhone, so probably not as good as a proper meter, but above the unit it measures 75dB. Near the outlet, 67dB. 3ft away, 65dB. If I close the bifold door in front, then at 3ft away it's 52dB. The app says "quiet home" for 52dB... but it certainly doesn't feel quiet to me. Maybe it's partly the frequencies that make it seem worse. When the compressor is off, the room is more like 30dB.I have the Rheem and it is whisper quiet. I can barely hear it running and have to stand right next to it.
Mine sounds more like mellow's AO Smith, I think. If not worse.
Edit: A google search led me to a couple posts of people commenting on the current generation being loud. One person described it sounding like "an industrial ice maker at a cheap motel." Seems about right.