but another app where those variables arent initialized on app -> on start during preview mode (f5 triangle)
so my power app APP on start property field is not initializing variables in preview mode for one app , but it is for another app

but another app where those variables arent initialized on app -> on start during preview mode (f5 triangle)
so my power app APP on start property field is not initializing variables in preview mode for one app , but it is for another app
Are you running the OnStart? When you are designing the app, you need to specifically perform the OnStart action in order for it to work. Simply doing a preview will not perform the OnStart.
I hope this is helpful for you.