I was in the same boat as you, normal Airpods stayed in my ear while running but the Pro Airpods kept falling off. I then found some third party foam tips on Amazon and that made the Pros feel invisible like normal Airpods.
Do you mind linking those third party eartips? I am in the same boat as you, original airpods fit me like molded, I could jump and run with not even a hint of earbuds moving inside the ear. While airpods pro tend to wiggle and not stay fully in.