According to this CNN article, the record has been broken because of the COVID-19 outbreak:
On March 14, French airline Air Tahiti Nui flew the longest ever scheduled passenger flight by distance -- transiting 9,765 miles across the world from Papeete, in Tahiti, French Polynesia, to Paris' Charles de Gaulle airport.
This one off milestone was a direct consequence of the coronavirus-induced US travel restrictions.
This route usually involves a scheduled stopover at Los Angeles International Airport (LAX). But when an airplane stops over in the US, all passengers must alight the aircraft and proceed through US Customs and Border Protection before they're allowed to advance on with the next leg of their journey.
Current restrictions rendered this part of the journey untenable, so instead, flight TN064 just carried straight on, departing at 3 a.m. local time from Papeete airport and arriving in Paris at 6:30 a.m. local time on March 15.
This is a scheduled flight, but a one time deviation from the schedule (though the situation may continue to be like this in the near future).