i wanted to get firefox to wayland because of scaling.
(sadly keepass does not work with that).
So i wanted to follow the link: Firefox - ArchWiki and put MOZ_ENABLE_WAYLAND=1 into the /usr/share/application but that did not work.
Since it’s an environment variable, you need to set it with export in your .bashrc or bash-profile or any file where you define those variables, like that:
export MOZ_ENABLE_WAYLAND=1 # or 0 if you wanna unset it
…and copied and pasted the command without understanding it. Please read the Arch wiki article linked in the Reddit post. If you have questions, feel free to ask.