Does anyone have experience with “the red things”?

When my son was around four he started seeing “red things” floating towards him in the air, only ever when I was tucking him into bed and saying goodnight. They scared him so badly he would say “mama the red things, they’re coming towards me” or “mama the red things are mean and they want to get me” and I’d ask him to describe them and he would always look to a specific spot and then would get higher pitched as he got more frightened as they “came towards him”. I would hold him and reassure him until he fell asleep which could take a while. He never talked about them during the day or to anyone else though I did try and gently ask about them once or twice. Fast forward a few months, my two year old started crying one night, in her own room, saying “the red things” were coming for her. She had never heard my son talk about them. I have audio because I would describe it to my husband and he thought it was creepy but just sort of weird, until he heard the audio then it scared the shit out of him too. They eventually grew out of it, and we also moved houses (unrelated). Anyone else experience something similar?