It’s breaking the access to the website and not a good look for the “app store for Linux”. A lesson in central points of failure?
FWIW … it is fixed now.
It’s broken on the www.flathub.org domain but not on just flathub.org by itself. Despite browsers trying to get rid of www its still commonly used.
Yeah, it isn’t a good look for flathub. I looked at the certificate and the Subject Alternative Names section was missing the www prefix. Why they’re not using Let’s Encrypt and certbot beats me because this could all be automated.