Hey there thanks for the compliments.
I will also CC @JoyfulFlowerMary and @coolerthanbatman123 as they were discussing this issues as well.
Here is a video of the issue.
Your suspicion is right. Just found out about this fps plugin controlling tool which is very useful.
From the video I can conclude that it is caused by the dampening not being sufficient while the spring force is very high which is done to mimic humanoids.
self._vectorSpringDragForce.Force = Vector3.new(0,-rootPart.AssemblyLinearVelocity.Y*damping,0)
I will try to implement a physics sub step algorithm similar to the video below. I believe it explains the issue more clearly.