Nanopool of all pools. As far as I can tell both moneroocean and nicehash are still mining zephyr, we've lost some hashes there, on top of low price and high electricity costs for many, heat waves for many others... all in the middle of August when "nobody" is watching. Looks like a potential perfect storm.

Still, I would bet my ass THEY are still asleep. 51% attack makes no sense other than damaging the network. No gains to be made for any participants, zero incentives.