An additional problem with this is that they use A3C here for trading. A3C is known to not be suitable for adversarial environments (e.g. board games, like Chess).

I wrote a paper that demonstrated that A3C is as exploitable as a uniform random strategy in board games (specifically, some poker variants): https://arxiv.org/abs/2004.09677

(Exploitable is a technical term that is defined in the paper; basically, it's "how much can someone who knows everything about your strategy beat you by?")

So I would be very surprised if this survives contact with other traders.