In this case, the user won't receive any commission until his rev share balance becomes positive for the losses of the referred users. The casino won't take anything from his own deposited funds. Winna affiliate program terms say this:
9.3. Negative carryover will continue to roll forward month to month until the cumulative NGR balance becomes positive. No rev share Commission is payable while the cumulative NGR remains negative.
those terms are written in a weird way so they can fuck over their affiliates if somehow their players get super lucky, and they don't want to waive it off.
from what i know, the industry standard for revshare deals, is no negative carryover and if you as an affiliate end the month in the negative, it resets to 0 the next month.
tbh, anyone promoting winna with a revshare deal that has negative carryover is kinda retarded.
The bug I reported via their official bug report email 3 weeks ago is finally fixed, yet no recognition, response or anything from their side.
Took them long enough, almost 3 weeks to fix it but not even a reply or anything is pretty weak I must say. Since they obviously cared at some point ( otherwise they wouldn’t have fixed it ) I think at least thanking people is an adequate action.

this is winna we are talking about, so i'm not surprised.
if they reply with a "thank you" that would be acknowledging that you reported a valid bug/exploit to them which also means they would need to give out a bounty for it.
but i guess they would rather fix it in silence and pretend it never existed.