Hello Grueneman,
Thank you for using Apple Support Communities! I understand that email apps are displaying upside down on your iPhone and you've recently updated your device to iOS 13.1.3. You've come to the right place for a resolution.
Let's start by forcing the affected apps to close, then restart your iPhone:
When you launch the apps again, do they still display upside down? If so, let's test if there's any change when you change the screen orientation on your iPhone:
Change or lock the screen orientation on iPhone - Apple Support
Keep us posted on the results.
Cheers!