The image drag and drop of the iPadOS (beeing able to drag and drop any image you want to any other app) causes images to lose their transparancy!
This is a major inconvinience, and clearly a Bug, as proven in the first + second
Video 1 (showing how it works in every app. (also works in Ankidroid + Windows Anki):
Video 2 (showing the exact -very same- file being chosen once with drop&drag and once with “select from files”)
NOTE: The same issue also happens, if the file is added from the Photos app. It only works, when the file is opened from the “Files” App.