Is there recourse for if a website blacklists Relay email domains?

[MegaScience]

Earlier I attempted to log into an account on a website I hadn't in some time. While the website doesn't directly take emails, it reads the emails from external services used to log in. I logged in through Discord and was met with a message that my email didn't have access to the site. I checked while logged out and my account was still fully visible, so eventually I changed the email of my Discord to a non-Relay email, tried again, and it let me in (including everything I had before, so it didn't treat it as a fresh account).

It isn't the first time I've encountered a website blocking a Relay email, albeit it's been somewhat rare. Still, it is frustrating, and had me thinking: Is there a formal method to report this to Mozilla or some body that would hold issue with it? Something akin to how we can report sites which intentionally exclude non-Chromium browsers from accessing them.