I used these two tips:
https://www.reddit.com/r/AirpodsPro/comments/1nopfx5/fixing_airpods_pro_3_clicking_sounds_with_foam/?sort=confidence
and:
"The clicking noise you hear comes from the rubber sticking to the rubber. This means that the inner rubber is touching the inner wall of the tip. I noticed it too. I have a solution for this: insert a piece of tissue paper between them. It works very well."
@NikoTsio
And that completely eliminated the clicking noise when walking.
So I think the problem is not software-related, but rather the materials Apple used to make the earbuds.
But **** it, as a perfectionist, it pains me to wrap my new AirPods in paper and foam. I paid $250 for them! Why should I have to modify them myself?