Strange UITextEffectsWindow eats away most of my events

I have an app that generally works fine, but I got field reports that some parts of the app becoming unresponsive at times.

After endless searching I was finally able to reproduce the situation, and found the following quite strange view hierarchy:

UIWindowScene - (Foreground Active)

UIWindow
UITextEffectsWindow
    UIInputWindowController
        UIInputSetContainerView
              UIInputSetHostView
              UIEditingOverlayViewController
                     UIEditingOverlayGestureView

Some internet search revealed that these are private classes probably linked to undo functionality introduced in iOS13.

What is happening here, and how to prevent that?

Thanks for any insight!

Klaus