Subconsciously I started using Chrome on my Desktop more regularly too, since the abhorrent state of Firefox on Macbooks trained me into using Chrome instead.
The Firefox developers don't seem to care about the state of Firefox, on macOS, to be honest.
For example - This is a bug report I made 7 months ago of an issue that would be quick to implement, yet make a noticeable difference in UI on macOS (move the Share menu to the File menu). Nobody has bothered to respond. https://bugzilla.mozilla.org/show_bug.cgi?id=1512851