Such a different problem with Fancy Bottom Navigation

Question

There is a problem about fancy bottom navigation. I have created this structure. I have 4 bottom part. One of the bottom part, there is a button, it goes second page but when i went second page, i pushed another bottom navigation bar part, page stays in the second page although changing bottom bar button. I do not understand this situation. Could anyone help me to solve this situation?

Here are my relational code parts=> Firstly I used, fancy_bottom_navigation: ^0.3.3.

return MaterialApp(
        debugShowCheckedModeBanner: false,
        navigatorKey: navigatorKey,
        home: Scaffold(
          body: Container(
            child: Center(
              child: _getPage(currentPage),
            ),
          ),
          bottomNavigationBar: FancyBottomNavigation(
            circleColor: col.mostLightPurpleAccent,
            activeIconColor: col.mostDarkPurpleAccent,
            inactiveIconColor: col.mostLightPurpleAccent,
            barBackgroundColor: col.mostPurple,
            textColor: col.mostLightPurpleAccent,
            tabs: [
              TabData(
                  iconData: Icons.dashboard,
                  title: "Panel",
                  onclick: () {
                    final State<StatefulWidget>? fState = bottomNavigationKey.currentState;
                  }),
              TabData(
                iconData: Icons.trending_up_outlined,
                title: "Üretim",
              ),
              TabData(
                iconData: Icons.trending_down_outlined,
                title: "Tüketim",
              ),
              TabData(
                  iconData: CupertinoIcons.wrench_fill,
                  title: "Bakım"
              )
            ],
            initialSelection: 0,
            key: bottomNavigationKey,
            onTabChangedListener: (position) {
              setState(() {
                currentPage = position;
              });
            },
          ),
        ),
      );
_getPage(int page) {
    switch (page) {
      case 0:
        if(Platform.isIOS){
          return CupertinoApp(
            debugShowCheckedModeBanner: false,
            title: 'Panel',
            home: FactoryDashboardScreen(locId: widget.locId,),
          );
        }
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Panel',
          home: Scaffold(
              body: FactoryDashboardScreen(locId: widget.locId,)),
        );

      case 1:
        if(Platform.isIOS){
          return CupertinoApp(
            debugShowCheckedModeBanner: false,
            title: 'Üretim',
            home: CupertinoPageScaffold(
              child: ProductionScreen(locId: widget.locId,),
            ),
          );
        }
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Üretim',
          home: Scaffold(
              body: ProductionScreen(locId: widget.locId,)),
        );

      case 2:
        if(Platform.isIOS){
          return CupertinoApp(
            debugShowCheckedModeBanner: false,
            title: 'Tüketim',
            home: CupertinoPageScaffold(
              child: ConsumptionScreen(locId: widget.locId,),
            ),
          );
        }
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Tüketim',
          home: Scaffold(
              body: ConsumptionScreen(locId: widget.locId,)),
        );

      default:
        if(Platform.isIOS){
          return CupertinoApp(
            debugShowCheckedModeBanner: false,
            title: 'Bakım',
            home: CupertinoPageScaffold(
              child:MaintenanceScreen(locId: widget.locId,),
              // child: LoginApi.userUnits.contains(3) ? MaintenanceScreen(locId: widget.locId,) : NotAllowed4Dash(),
            ),
          );
        }
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Bakım',
          home: Scaffold(
              body: MaintenanceScreen(locId: widget.locId,)),
        );
    }
  }

Padding(
                    padding: const EdgeInsets.all(16.0),
                    child: SizedBox(
                      width: width,
                      height: height*.24,
                      child: ElevatedButton(
                        style: ElevatedButton.styleFrom(
                          padding: EdgeInsets.all(32),
                          shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(75)),
                          primary: colFr.frAuroraGreen,
                        ),
                        child: Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: [
                            Text("Çözümlenenler",
                                textAlign: TextAlign.center,
                                style: TextStyle(
                                    fontSize: height*.03,
                                    color: CupertinoColors.black)),
                            Text("122",
                                textAlign: TextAlign.center,
                                style: TextStyle(
                                    fontSize: height*.03,
                                    color: CupertinoColors.black)),
                          ],
                        ),
                        onPressed: () => {
                          Navigator.push(context, CupertinoPageRoute(
                              builder: (context) => SolvedScreen()))
                        },
                      ),
                    ),
                  ),

The code seems independent but it is united parts which are problematical. If you want to examine the full code i have example app in my github repos here is the link: https://github.com/androloper/mobile/tree/main/hencoop_watch_app