As discussed in T117970, the "last modified <time> ago by <user>" feature in Mobile is quite cool - I really appreciate that it's time-relative. However, what is completely unclear to the mobile reader is that both the timestamp and the username are links. See attached image for an example.
I'm referring to the section in green:
On my iPhone, pressing the words "5 hours ago" will take me to the article's history page, while pressing the username will take me to their special:UserProfile page. Neither of these actions are obvious on mobile because there is no visual indication that they are links - either by colouring them differently, or by underlining them, or some other method I can't think of.
In contrast - if you look at the mobile view on a desktop computer, then it is possible to hover the cursor over those words - at which point they are given an underline (and the URL preview shows in the browser, depending on your settings). This is NOT the case on mobile.
The only way a mobile-reader would discover these things are links is by accidentally pressing them, and then consciously working out what they'd done so they could repeat the action.