"If this helps you may want to install a proper shielded cable."

Good advice!

Greenfield flexible conduit between the ballast and bulb should tame it.

Any shielding solution will require a proper ground.
So buy a cheap Led, outlet tester and use it to check your ballast's outlet.
Your solution could be as simple as tightening the main grounding clamp at the service entrance or swapping the hot and neutral leads.

Aloha,
Weezard (retired IBEW)