The en main page is currently stuck at "Andrew Johnston", which was the featured article on Dec 26.
Probably caching/etag related. We have special handling for main pages inside the MCS to use action=mobileview instead of Parsoid.
After some debugging, I noticed that the m dot RB endpoint isn't getting updated but the regular RB domain endpoint is:
https://en.m.wikipedia.org/api/rest_v1/page/mobile-sections-lead/Main_Page <-- OLD content from Dec 26
Unfortunately, the app is using m dot domains right now. Please advise if that can be corrected in RESTBase or requires an app change.