Ever since I updated my project to UE4.25, the Unreal Logo appears first when I launch the app on iOS. I don’t know if this is an intentional change by Epic, but the screen displays Unreal logo for a few seconds before actually showing my app’s splash screen. I’m not using a custom launch screen storyboard, just a default 2048 x 2048 launch screen image.
Solved it here: iOS Keeping old launch screen and app icon after update - Stack Overflow
Turns out its an iOS issue, not UE4.