The UFO constantly tries to push away from the wall, only to hit the other wall, causing this effect. This happens either on spawning it too close to a wall, or when you drive it into a wall.
Also causes Down Special to act a little weird while on it
#Galvan UFO does not like being between the buildings in Julesvale Skyline
outer mango
It's a lot more flickery looking than what the video shows since Discord has a lower fps for videos