React-native-navigation: [iOS] Topbar flicker when changing tabs and then pushing on that tab's stack

[ItsNoHax]

Issue Description

I'm running into a weird bug which has a randomness factor to it. It seems to be some kind of race condition when updating the currentTabIndex and then directly pushing on the newly navigated tab's stack. (Only reproduces in Release version)

Gif of it happening 1/3 times:

Steps to Reproduce / Code Snippets / Screenshots

Reproduction branch: https://github.com/ItsNoHax/react-native-navigation/tree/reproduce-white-topbar-flash

Click on green button 'Update merge options and push' -> Observe topbar -> Click on Layout tab -> Repeat till topbar flickers grey

Code snippet:

    Navigation.mergeOptions('bottomTabs', {
      bottomTabs: {
        currentTabIndex: 2,
      },
    });
    Navigation.push('navigationStack', Screens.FlatListScreen)

EDIT:
It seems as a temporary workaround I can add a 100ms sleep between merging options and doing a push. Not the prettiest, but it works.

---

Environment

• React Native Navigation version: 6.4.0
• React Native version: 0.61.5
• Platform(s) (iOS, Android, or both?): iOS
• Device info (Simulator/Device? OS version? Debug/Release?): Simulator/Device, 13.3.1/13.4, Release

[ItsNoHax]

I went ahead and updated to XCode 11.4 and iOS 13.4 and still observing the same regression.

[dozoisch]

Just want to update versions, the same issue is still present on

React Native Navigation version: 6.8.0
React Native version: 0.62.2