You’re seeing the result of the Humanoid’s internal forces acting upon the player. You can stop the Humanoid from applying a downward force by setting their state to Physics or making them PlatformStand, though they will also lose regular mobility which you will need to account for.
In any case: seeing your exact setup and the behaviours you’re running into in the form of a video would be helpful to attempt to replicate your environment and do some tests based off of that. Without any of that, it’s difficult to actually give you any insight to how you could fix this.