So this is a known bug and not very easy to work around sadly 
It’s because of a limitation of Apple’s system component UINavigationController. All navigation screens must have a navigation bar (header). Given that the feed screen doesn’t have any header by design, we are “hacking” the navigation bar by making it transparent. The problem appears when you perform an interactive transition. The app updates the colour of the navigation at the beginning of the transition and turns it transparent.
We’re going to add this topic to our iOS weekly meeting agenda to discuss it and try to find a better solution for this.
I can’t give you a timeframe because fixing this might involve a big change on how we build navigations in the app, or a design change.