This specific "12.x" version is designed only for iOS 12. Other versions of FilzaEscaped exist for iOS 14-16. If you'd like more specific information, let me know: Which iPhone model are you using?
It is strongly recommended to only modify files within /var and avoid changing files in the root / directory unless you are experienced. Frequently Asked Questions Filza Escaped 12.x
FilzaEscaped is typically installed as an IPA file using third-party installers: This specific "12
Supports early iOS 12 versions, including A12 devices. It is strongly recommended to only modify files
Edit system files to change app icons, user interface elements, or carrier text.
It does not permanently void your warranty because it does not alter the system partition permanently. However, you should remove it before taking your device to Apple.
Read/write access to system files, application data, and internal configurations.