It was the same for me. They did have a message saying that they would be down for maintenance prior to going down.
I'm surprised that no one is posting anything about this issue since it's been a few weeks and it still hasn't been fixed.
Nitro NFL Survivor Pool -- Opening of new NFL season is fast approaching! 🏈
I had no choice but to miss out on the survivor pools due to this cloudflare error still appearing on my end. Anyway, best of luck to the participants who got in this season.