Radio "glitches/interference" is caused by multiple things. Metal on metal contact (usually the throttle clevis or rod touching the engine or a metal clevis on a metal throttle arm (bad juju)) also failure to isolate the antena wire and this can be challenging to find some times. I once got glitchy performance from plane that the engine bearings were failing in due to the excessive metal scrapping going on inside the engine. I doubt it has anything to do with your digital servos.