From 29 November 2020 Sagecoach are changing its bus timetable due to the roads being clear during the pandmic.
Stagecoach bus number 255 from Manchester City Centre current and new timetable can be viewed here https://tis-kml-stagecoach.s3.amazonaws.com/PdfTimetables/XJAO253.pdf
It seems that bus service times from Partington will remain the same.
On observation we actually see am increase in traffic overall all over the borough although some people are still frightened to go on a bus.
Other services are to change slightly in Trafford and you can see all changes for your area here https://www.stagecoachbus.com/promos-and-offers/manchester/timetable-changes-from-29-november-2020