Strange navigation and tabar behaviour when animation

Hello,

I have a view controller container. When I transition from the first child view controller (a simple view controller) to the second one that has a tabbar and navigation bar, it appears that the initial position of the tabbar and the navigation bar are not the as expected, they are slightly outside the screen. See the GIF and the code. Do you know how can I avoid that strange animation? Or the root of the problem. Thanks.

        dashboardCoordinator = DashboardCoordinator()
      
        rootViewController.addChild(dashboardCoordinator!.rootViewController)
      
        let fromVC = onboardingCoordinator!.rootViewController
        let toVC = dashboardCoordinator!.rootViewController
      
        fromVC.willMove(toParent: nil)
      
        rootViewController.transition(from: fromVC,
                                      to: toVC,
                                      duration: 5,
                                      options: .transitionCrossDissolve,
                                      animations: nil,
                                      completion: { [weak self] finished in
                                      
                                        guard let self = self else { return }
                                      
                                        fromVC.removeFromParent()
                                        self.onboardingCoordinator = nil
                                      
                                        toVC.didMove(toParent: self.rootViewController)
        })

Animated GIF

https://i.stack.imgur.com/Qo5Mn.gif

Thanks a lot.