Edit: This has been fixed. Thank you admins.
If you visit lemmy.nz via http rather than https, you get a Bad Gateway error. It should be redirecting to the https url. Not sure who’s in charge of the domain and server, but it can usually be done in either of those places.
Thanks for reporting this! As mentioned, re-enabling cloudflare seemed like the easiest way to fix this (and should help make the site feel faster too).