Long articles can be split (https://en.wikipedia.org/wiki/Template:List_has_been_split). The resulting text box reads "This list has been split for improved performance."
But, the Split box is not being displayed on pages in the iOS Wikipedia. This problem was seen on iPhone 6 and iPhone X on 15-Jun-2020, on the latest version 6.6. I don't know whether this feature never worked or whether the bug is new to this version of the app.
Steps to reproduce:
1. Access the Wikipedia native app version 6.6 on iPhone X or iPhone 6.
2. Navigate to any Wikipedia page that contains the 'Split' section, for example:
List of unnumbered minor planets 2004 T-Y
List of unsolved murders in the UK
List of The Simpsons episodes#Episodes
Expected:
3. Split box should be visible on each of these pages.
Actual:
3. Split box is NOT visible on any of these pages, it is missing.