Kindle app on iPad mini 6 and iPad Air

I am seeing an annoying behavior on my iPad mini 6 when reading a book with the Kindle app: the ‘affordance’ (line) at bottom center of screen does not go away after dismissing reading options (it disappears a few seconds after opening a book, but bring up options makes it re-appear and then it doesn’t go away after that). On iPhone with TouchID it does not have this issue.

Wondering if this happens on the iPad Air 4th generation as well, since like the mini, it lacks a Home button and thus will display the line when the dock is not shown and the app doesn’t make it go away.