iOS 11.4 privacy & security fail / data protection bug

Demonstation of data protection fail in iOS 11.4 (but not exclusive to this version) that can expose your sensitive data.
Each time you press the HOME button to go to the App Switcher view, system takes a screenshot of current app so you can see in the app switcher the state that each app was put to background. Those screenshots are stored in the system until overwritten, app gets deleted or (most likely) app gets updated.
BUT if the App Switcher is loaded in horizontal mode, there's a separate screenshot taken for that view. As the horizontal view on iPhone is not used so often (at least by me), those horizontal screenshots are stored unmodified for months.
Few days ago, when I entered the App Switcher in horizontal mode, I've noticed a lot of old app screenshots with data I don't have/want to have anymore - old photos, Apple Maps destination, visited website, iMessage conversation...
Try it yourself, open a lot of apps in normal vertical view, put them all in background in vertical view (this will overwrite only last vertical screenshot), then open one of the apps that can be used horizontally (best if you choose one that you never used horizontally), rotate your phone, go to App Switcher and scroll through the memory lane.
Of course since your phone is protected by passcode, TouchID or FaceID, you are the only one that can access this data. But on the other hand if an app can have additional security features (like Notes with pass/touchID protection) it should prevent system from taking screenshots of the protected data, right?