My right joycon does the same, my friends with Switch told me to clean underneath the sticks with a contact cleaner, but I have no time to clean it so I ended up buying a new pair of joycons. Turns out the first batch of Switches have defective Joycons. The new joycons I have now has a different texture and matte-like finish unlike my first joycons, and my new ones work perfectly fine. Are these your first joycons?