Thanks for the issue report! I've just this minute added some alternate image formats. Now it should serve AVIF (2MB), WEBP (4.5MB) or PNG (7MB) in order of preference. I guess it could also be security settings as I serve that huge image from a different subdomain for CDN purposes. Do you have any luck right clicking on it and opening it in a new tab/window?

edit: checked and confirmed page working OK for me in Firefox 115.0.2 (64-bit) on macOS 12.6.7 Monterey.