From a manufacturing point of view it's more expensive to make a harness for each application. So I figured it was the same between both vehicles.
A dealer or a garage with a Tech II may be able to fix the odometer reading.
Being that it doesn't do this on a completely vanilla install of Pale Moon on any of my three computers, it's not something wrong with the forum software.
EDIT: As suspected, it's something with that browser. https://forum.palemoon.org/viewtopic.php?t=14012