According to the TTC.ca website:
Effective until June 24 –
Due to continued construction at Humber Loop, service after 10:30 p.m. on weekdays and Saturdays, and all day Sunday, will be extended to Ellis Avenue and The Queensway.
Buses will turn back to the route via The Queensway, Ellis Avenue, Lake Shore Boulevard, and Windermere Avenue. Customers can transfer between 501 Queen and 80 Queensway service at Ellis Avenue and The Queensway.
#80 Queensway Bus Schedule can be accessed here.