Looking for app programmer ( maintenances ) with monthly payment

We have a project its mobile application working in food delivery and taxi mode with 2 admin pages ;
App is ready and working fine . We need a programmer has knowledge in those languages to handel the app in case we face a bug or issue help us to solve it .
We are thinking to pay him fix monthly rate

The app and admin pages languages :-
Backend Node JS
Database MySQL
Order Panels Angular JS
Ride Panels PHP
Framework Laravel
User Website Angular 10
Designing HTML+CSS
Server side Rendering Bootstrap
Android Kotlin+Java
iOS Xcode+Swift

If you are interested please contact me