None of the above. Unless you have metal geared servos.

Glitching is caused by EMI - Electro-Magnetic Interference. By definition your own receiver and transmitter cannot "cause" it - only be affected by it. It can be caused by any broad-frequency spark like from a car's sparkplug, nearby high-tension power line or a large electric motor (garage door opener, drill, vacuum cleaner, car alternator, etc.). Two pieces of metal rubbing together inside the airframe from vibration can also cause glitching. That's why a lot of pilots won't fly metal-geared car servos.