Wow, I think you spotted that right, and they always wait to just before the deadline to request a revision too.
IMHO, it’s resellers doing this. They order multiple gigs so they can give their client choices. If the client doesn’t choose your work, then the Buyer orders revisions from you until you’ve lost so much on the order that you cancel rather than continue to bleed money and risk a bad review (even if you don’t offer revisions).
That bull crap happened to me last week.
So, I’m contacting their client and telling them they need to pay me for the work I did on their behalf, and I’ll send them to my Fiverr gig so they can reimburse me there. There’s nothing in Fiverr’s TOS that says I can’t do this and I’m sure Fiver won’t be bothered by any money I recover.
Me and Fiverr need to get paid!