The page takes a good 10 seconds to finish loading before the cookie permission prompt displays. I think the time is related to rendering out the canvas element that zooms/pans/rotates as you scroll.

It's difficult to compare Windows/Intel with MacOS/M1 because graphics hardware and driver software most likely are different. You could try disabling Firefox from using hardware acceleration. This is a potential workaround for incompatibilities between Firefox and your graphics card/chipset driver software. This article describes where to make that change: Firefox's performance settings. This will take effect the next time you exit Firefox and start it up again. Any difference?

Changed the performance settings, but no change in response. Total freeze. No cursor movement, no movement of the "tick-tock" indicator on the tab bar, no Cookies dialog. Keystroke commands don't allow me to quit Firefox or access the computer. Have to manually shut down with long-press of the Touch ID button to restart the system before I can do anything.

I don't have any new guesses about what is going on with that page. Have you noticed problems on any other pages, any pattern?