App volume soft at 100%

I'm a professional musician and (usually) use my phone as a metronome. The metronome app starts a couple clicks at full volume, and then goes soft. Adaptive sound is turned off and I've monkeyed with the developer options to no avail. I also tried a video call on Google Duo with my parents and they could barely hear me so I had to switch to my iPad (LOL) which worked fine.

(I also posted a week or two ago that my AirPods volume is soft on my Pixel at max volume, too, and can't get that fixed either).

I've used the Pixel for two months and it's been nothing but frustrating. I don't know why I switched from OnePlus ...