I've noticed that bone conduction has increased when I walk, every time I set down my fot when walking there is this "thud" that is so common with in-ears but wasn't when my Airpod Pro were new. Then I tried the ear tip test, it failed on both ears, first I thought it was the new 2D15 firmware screwing with things but after some googling and finding all these threads complaining about this issue, I decided to try cleaning the inner vent with Q-tips and isopropylalcohol, it didn't do much difference for the bone conduction issue but at least the test did pass on several occasions on the right pod this time. I finally tried some Blue Tack treatment, viola, both pods test PASSED and now there is much LESS audible bone conduction from my feet when walking.
This is an obvious design flaw with the Airpod Pro. I REALLY hope they'll fix this in future revisions as I now will have to carry around a small bit of tack tucked into the round holes in the case for occasional cleaning.
Can I ask how long you've had them? I had mine for six months before trying/realizing I could try the blu tack, and while I got some improvement, it's not back to passing the fit test or the great initial noise cancelling I had for the first month of having them.