found the glitching issue, need help solving it

[BrianG]

You will usually get less glitching up close because the radio signal is stronger. Is the antenna wire near the motor or power wires? Those high current wires, especially the motor wires, can emit RF noise which can cause problems with some radios, especially AM.

The cap in third channel will simply even out the U/BEC voltage so there are less dips under load. It can also help filter out noise coming down the BEC wires.