Was the 140 runtime inaccurate, or has the movie been edited?

Probably was edited. Justin Kurzel intended to do at least a 2 hour movie. This new runtime is far from being 2 hours, considering that 10-12 min. will be credits.

The 140 min length was rumored, so it's hard to say...but considering the glut of films out there right now, there's a possibility that they trimmed the film to squeeze out another showing per screen per day. With Rogue One in 4000+ theaters and Sing and Passengers each gobbling up a sizable number of screens as well, the biggest constraint on AC's box office performance at this point is the number of showtimes they're physically able to get. But I don't know...

It was never confirmed by Kurzel or someone else that worked on the movie that it would have a long running time. they were just rumors.