If the app is using the Background App Refresh entitlements [1] (Background fetch / background processing) then it is possible for iOS to update the screenshot

If the app is using the Background App Refresh entitlements [1] (Background fetch / background processing) then it is possible for iOS to update the screenshot for the app switcher periodically even when the app is in the background Messages does this, as you will notice that an active conversation tends to be up-to-date in the app switcher [1] https://developer.apple.com/documentation/uikit/app_and_environment/scenes/preparing_your_ui_to_run_in_the_background/using_background_tasks_to_update_your_app https://developer.apple.com/documentation/uikit/app_and_envi...