So in terms of making the game feel like everything is smaller but you, the gravity is fine BUT not when it comes to physics.
I know Minecraft and physics is not always compatible, but gravity is something very basic.

It has to do with the way you handle motion. When you scale up your base/motion you fall faster too. The Same applies when you shrink, you fall slower.
Normally the Size/Speed should have no effect on your gravity. Everything falls at the same speed (Not considering air resistance, but that is not important here)

I would split up motion into motion and gravity, so it can be affected differently. Also, gravity should not be affected by base.

I hope this was helpful. It is not meant in any bad way ^^

I can notice the same thing, albeit with Pekhui 2.2.0. I would also like to suggest that pekhui:gravity be responsible for scaling fall damage (i.e. fall distance) since that is related to gravity and is dependent on gravity in reality.