On iOS 16.5, when the app is on the default theme settings, it doesn't update the theming according to the systems preferences for dark or light mode.

We received this bug report from a user and could reproduce it on iOS 16.5; other OS versions seem to be working as expected.

Steps to replicate the issue (include links if applicable):

• Update OS to iOS 16.5
• Set the app to the default theme
• Switch the system appearance between light and dark mode

What happens?:
The app is not updating to light or dark mode as the system preferences change.

What should have happened instead?:
The app should update to the light or dark mode according to the system preferences

Software version (skip for WMF-hosted wikis like Wikipedia): app version 7.3.0

Other information (browser name/version, screenshots, etc.): iOS 16.5

Video: https://drive.google.com/file/d/1GSn81Rf-_d35-8GLYHppBEZ_ijOFsZ-k/view?usp=drive_link