I’m so sorry that this has happened to you but I am also pleased that I am not the only one who has this happen. (Though not to this extent.)
First off, what is this buyer ordering? Is there any way to use their brief to identify where whatever is being ordered will be used?
If the answer to the above is yes, the scammer will be a reseller passing your work off as their own for a premium. What you can do in this case, is contact the end client and notify them of the situation. They will likely then be enraged and cut of dealings with the scammer. - The end result being them placing no more orders.
I haven’t done this in such a direct way. In this case, if you do this make sure to clear it with CS first, but be affirmative. Tell them this your business and this is what you are doing to stop it being ruined since they are unable to do anything.
If you don’t know where or how the work being requested is being used, entrap the buyer. Like you say, scammers like this are dumb. Play dumb yourself and say something gushing like:
Thank you so much for your order! I believe in 100% satisfaction and I’m about to start on this right now! I just need…
Another thing you can do is raise all your prices to above $50. (Temporarily). You might have to take the hit with a few missed orders from genuine clients. However, keep them up long enough and your scammer will likely feel less inclined to put as much cash on the line. As well as this, you can also pause gigs immediately after receiving a message. Then when the scammer messages tp say they can’t order, tell them everything is fine on your end but because of a security issue, some buyer accounts are being blocked by Fiverr.
If you do the above, this buyer will be forced to keep on creating more and more accounts, each of which will eventually grow a bit irksome. (This and increase the chances of Fiverr picking up fraudulent activity).
Other than the above, all you can do is cancel all suspicious orders as soon as they are placed. I’ve done this twice over the past 2-days for the same reason as you. - 100% sure its the same buyer who last canceled an order after delivery, they rush in and order a service without discussion and communicate identically.
Whatever you do, good luck!
Also, as a note to Fiverr: Do you see the massive inherent flaws in the St Levels system yet???
Edit: Seeing that you know where this content is being used, think about sharing a link on your own social media channels and freelance forums on places like Reddit. Explain the situation and cause your scammer social media Armageddon by encouraging your own followers to review your scammer as they see fit.