Reported on OTRS - https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=10681368
@cmadeo also worked on this ticket and asked the user to provide screenshots which they did.
1. Load an article with a location image and pushpin (example: Lilliput Glacier, in quick facts)
2. View the image and pushpin
3. Tap on the image to view it in mediaviewer (fullscreen)
The pushpin remains visible
The pushpin disappears
Frequency - 5/5