It's been widely reported [0]. And as I said I feel like it's still a fair deal. Some HFT's get my orders and they know I purchased 2 AMZN yesterday a few seconds before it executed. In return I get to trade for free on their platform.

[0] https://www.bloomberg.com/news/articles/2018-10-15/robinhood...

Are you sure it's illegal in all cases? I was under the impression this was standard practice. https://www.cnbc.com/2014/03/30/michael-lewis-flash-boys-and...