The Romans left Britain early in the 5th century (409 AD), so maintenance ceased, and that assumes that they’d maintained it after Septimius Severus died of old age and illness at York.
As the article notes, the route continued in use thereafter, but by the 14th century the road had apparently been buried by erosion and whatnot. The ford over the river would have kept the route relevant.
ths
that’s where i get confusion, if it was an important enough road to be Roman Built Spec, i’d think it would be a main thoroughfare that wouldn’t go out of use, unless there was a shorter/faster route