Ok, I think I figured out what happened:

The name "Brushy Springs Trail" comes from the official USFS map, but the USFS map itself has the trail descending into the basin east of Box Elder Peak and south of Bob Stewart Peak. However, I was unable to find any trace of the trail on the Strava heatmap or on any aerial imagery, so it doesn't seem to actually exist in most places.

The part that remains on the map is the one part of the official Brushy Springs Trail that appears to actually exist nowadays, between the main ridge and Bob Stewart Peak. The extra bit that I accidentally deleted is not part of the Brushy Spring trail; seems like I probably meant to mark it as informal but instead deleted it entirely accidentally.