Steps to replicate the issue (include links if applicable):
Open https://en.wikivoyage.org/wiki/Paris?useparsoid=1 and look at the first "Map of Paris".
What happens?:
Below the map, there's a marker "'"UNIQ--maplink-00000004-QINU"'".
When opening the map in large format (by double-clicking on it), the title of the map is "'"UNIQ--maplink-00000004-QINU"' Map of Paris".
What should have happened instead?:
The marker should be replaced by a maplink to open the map in full page. The title of the full page map should display "48°51′28″N 2°20′24″E Map of Paris" instead of the marker.
Note
There's a non-zero probability this is related to T345568, but it seems to deserve its own investigation to either update that bug or to keep this one as a stand-alone.
After investigation, it seems related to StripMarkers and legacy template preprocessing.