Formula mongodb has been removed from homebrew-core. Check pr-43770 from homebrew-core
To our users: if you came here because mongodb stopped working for you, we have removed it from the Homebrew core formulas since it was migrated to a non open-source license.
Fortunately, the team of mongodb is maintaining a custom Homebrew tap. You can uninstall the old mongodb and reinstall the new one from the new tap.
# If you still have the old mongodb installed from homebrew-core
brew services stop mongodb
brew uninstall homebrew/core/mongodb
# Use the migrated distribution from custom tap
brew tap mongodb/brew
brew install mongodb-community
brew services start mongodb-community
Check mongodb/homebrew-brew for more info.