EDIT:
I looked it up, the issue is that homebrew explicitly doesn't want .app formulas: https://docs.brew.sh/Acceptable-Formulae#stuff-that-builds-a...
IDK what they expect. Every open source application developer needs to pay $99/yr now?
I mean you can always get the DMG from the releases on GitHub, so I guess we can just point people there and abandon homebrew. https://github.com/alacritty/alacritty/releases