For some reason, my Z axis is really wobbly after support told me to loosen the 4 4mm screws on each Z threaded rod. Is this normal? Here is a video
I think their usual advice is to loosen the screws, run the Extruder up to the top and down a few times, then tighten the screws again, not too tight. This is usually to level it up a bit.
It will wobble if left loosened.