There is a question with the title:
HTML form using <table> or <div>?
But it is shown in the Feed like this:
HTML form using or ?
In the following screenshot you can see that it is handled correctly when the title is shown for a reputation notification, but incorrectly as the title of a reply notification.
On the other hand a question title containing "<string>" will show up correctly.
It seems that HTML elements, that are stripped in the content editor, are stripped in the title of the iOS app as well, instead of escaping them.
I couldn't check this on Android. Maybe someone can verify this for the Android app. Thanks for your help, it works correctly on Android, so this is only about the iOS App.