Why the view keeps flashing when using jetpack navigation with Compose?

Composite navigation recomposes both disappearing and appearing views during transition. This is the expected behavior.

You're calling navigate on each recomposition. Your problem lays in these lines:

if (viewModel.isLoginSuccessful) {
    navController.navigate(Screen.AccountsScreen.route) {
        popUpTo(Screen.LoginScreen.route) { inclusive = true }
    }
}

You shouldn't change state directly from view builders. In this case LaunchedEffect should be used:

if (viewModel.isLoginSuccessful) {
    LaunchedEffect(Unit) {
        navController.navigate(Screen.AccountsScreen.route) {
            popUpTo(Screen.LoginScreen.route) { inclusive = true }
        }
    }
}

Check out more in side effects documentation.