If they go through arbitration they'll end up like DoorDash [1].
[1] https://www.latimes.com/business/story/2020-02-11/doordash-a...
[1] https://www.latimes.com/business/story/2020-02-11/doordash-a...
If not, it's probably safe to assume the consumer has to pay the fee.
Seems like something any financial lawyer would have checked the box on prior to making a HUGE announcement, so it's pretty plausible that Robinhood has no ideas about FINRA's laws about arbitration...
[1] https://www.forbes.com/sites/ronshevlin/2019/01/02/the-robin...