I think the 302 response has a CORS issue, so the browser doesn’t follow the redirect. The CORS tester makes requests from the server, so it won't be stopped by a CORS issue in the 302 response.
Thanks, Cody. Yes, this is fair enough, given that NIP-57 doesn't mention HTTP redirects. However, Alby themselves are recommending this: https://guides.getalby.com/user-guide/alby-account-and-browser-extension/alby-account/use-your-lightning-address/own-domain#:~:text=For%20advanced%20users%2C%20we%20recommend%20setting%20up%20a%20redirect%20rather%20than%20hosting%20a%20copy%20of%20your%20lightning%20address%20data
I know I'm asking a lot, but would you mind changing this line:
To:
const res = await fetch(lnurl, { redirect: 'follow' })
If it works, I can try to chase after other client devs! 🤣
Discussion
TIL that Cloudflare redirect rules don't play well with CORS. I've now implemented a worker with full blown CORS. Can you clear your cache and try again? (Sorry for the hassle)