Default WebGL fullscreen button not working in Firefox

I’ve built and embedded a WebGL project on my website. On Chrome and Edge the default fullscreen button works fine. I don’t know if this is a common issue, an issue with my project (which has no scripts relating to fullscreen mode), an issue with the website/html, or if there’s an issue with the build settings.

Has anyone else had this issue?

Having the same issue. Also if I use the Screen.fullscreen function ingame I do get FireFox to switch to fullscreen but my screen is scaled to about 300% from how it’s supposed to look.