On the IOS/Android app for Confluence, when the app is minimized, a KTX file (screenshot like) is created to be used on the multitask screen and any other animation.
This image file holds the information from the last visited page and it's stored on the system storage (in case of a missing device, this can cause data to be stolen). It will be good if there is an option to not use the screenshot from the last screen, but rather another image.
The KTZ image is described in here:
This is how you can substitute the screenshot like image, by another image, like a logo or something:
How to do it in Android as well: