A friend of mine bought IEMs with a microphone (Moondrop Chuu) and it would pick up radio frequencies that you could hear through a voice call. These didn't end

A friend of mine bought IEMs with a microphone (Moondrop Chuu) and it would pick up radio frequencies that you could hear through a voice call. These didn't end up fixing it, I suspected it was bad grounding but we never ended up solving what the root cause was.