It's caused by the site owner blocking cloudflare dns. There's a whole drama about it but I'll spare you the details. Switching to any other DNS provider should fix it.
My understanding is that webservers have no idea what DNS I used to resolve an IP. I understand that different resolvers could return different results, but either way I am not using CF at all, only a local bind resolver with no forward/recursive resolvers in use.
The open source version of bind does not support it according to their docs I read, but for privacy reasons I would not be using it anyways.
I still don't see how DNS would affect this though, because the domain still resolves, and it loads the CF turnstile page, it just never grants access no matter how many times I click "not a robot."
Unless maybe they had some kind of unique setup where non-ECS requests were resolved to IPs that just always gave you looping captchas intentionally... but somehow I doubt that is happening.