This seems perfectly fine. A list of disposable email domains should contain disposable email domains like Firefox Relay, iOS "Sign in with Apple", Fastmail's random e-mail generator and others. Weird that Apple's domains aren't on the list, though. Hell, Gmail and Outlook should be on the list as well, because creating email addresses there is so quick and easy they might as well be considered throwaway services.

I'm not sure what the point of that list would be other than to drive users away from your service, but hey, if you want to be a dick, you're perfectly allowed to do so.

Edit: as written here: https://github.com/disposable-email-domains/disposable-email... the list is not intended for websites where one needs to sign up for an account first, like free mail services. I suppose that means neither Firefox Relay, nor any other such service should be on the list.