"Kipchoge’s time didn’t go down as an official world record, sanctioned by the IAAF, due to variables like pacers entering mid-race and drinks being given to runners via mopeds."
"It wasn’t a road race, with runners completing 17.5 laps around the 1.5-mile Monza Formula One track. The Breaking2 project was held on the 63rd anniversary of Roger Bannister breaking the four-minute mile in 1954."

Despite the impressive result, it is not a marathon, but just a marathon-distance run. Bannister broke the record in an actual race, not a non-race special event.