When we lookk at the screenshot of the problem, it appears the navbar is dimensioned for the view that is stacked behind (smaller width and a few pixels above).
In the first (correct) screenshot, we see the view behind has a title. Not in the other.
How different are the views behind ?
In fact, I would guess this may come from the way IOS 13 handles UIModalPresentationAutomatic:
"Defaults to UIModalPresentationAutomatic on iOS starting in iOS 13.0, and UIModalPresentationFullScreen on previous versions"
Try changing the presentation to UIModalPresentationFullScreen and see what happens.
Read this for details:
The view controllers are set to formsheet, not automatic. Setting the presentation style to fullscreen does solve the issue but also gets rid of the "sheet" effect. I rather have the new formsheet or pagesheet styles and those keep having the little gap between the view and the bar.
I have uploaded a test project demonstrating the issue: https://we.tl/t-ojnTek5t7X
@TTAppDev I'm experiencing the same issue. Did you find a workaround and/or file a bug report?