I've been working my way through the Ethernaut levels in recent weeks, currently on Puzzle Wallet, but having had it work fine yesterday, I now get the following error (in the developer console) when trying to create a new level instance:
"Ethernaut contract not found in the current network. Please make sure (1) that you are using metamask, (2) that it's on a supported network, (3) that it is unlocked, (4 optional) From November 2 you can turn ON privacy mode (OFF by default) in Metamask settings if you don't want to expose your info by default. (5 optional) If privacy mode is turn ON you have to authorized metamask to use this page. and (6) then refresh."
I haven't changed any settings in metamask, from beating the previous levels.
I can always create a factory contract and deploy the levels myself, but I kinda like the web interface
edit: I've also tried using Brave browser and chrome, on both a linux machine, and macOS, all permutations result in the same "red" error message in the dev console...