I think the title is pretty reasonable. When given the choice between Wayland and X (because both are available, typically this is a Wayland + XWayland config)

I think the title is pretty reasonable. When given the choice between Wayland and X (because both are available, typically this is a Wayland + XWayland config) Firefox will now pick Wayland instead of X by default. Of course if only X is available (or only Wayland) it will continue to use what is available. I think "Firefox now prefers Wayland over X" may have been a bit more accurate, but that also has other possible interpretations.