Wifi says no internet--captive portal host broken

Suddenly my Teracube 2E is saying the Wifi has no internet. Network trace shows it’s trying to resolve captiveportal.kuketz.de and getting a DNS failure. Indeed, it doesn’t resolve for me (non-Wifi) and kuketz.de has had its domain registry change just today. Problem?

I told my phone to ignore and stay connected, and internet access works.

Looks like it happens because I’m pointing at Cloudflare. Just switched to Control D and it seems OK.