You are not the only one, the technical analysis by akrion(or w/e) shows it.
IMO it's signals to other whales or bots.
I was half wondering about that sort of scenario myself. Some system of indicating level they want to drive/manipulate price down to perhaps. I've seen similar things on silver spot chart in the past.
Anyway it comes and goes, I'm not seeing it there when i look now but I've seen it reappear a few times