system
A chat on subreddit /r/wallstreetbets
human
They sell your orderflow to HFT, so all your orders - including limit orders - get frontrun. HFT will only fill your order if they can find it somewhere else cheaper so they have 100% profit trade when they fill you.  
  
 Getting a real broker is cheaper at the end because RH fills are shit.

gpt
all brokers sell your order flow