Who knows how accurate these reports are, but "reshoots" are done on/built into almost every single blockbuster movie, good and bad alike. Sometimes it's as simple as needing certain reaction shots, clarifying certain plot points, etc. Things that are sometimes impossible to plan for until you see the whole thing cut together and it's like, "Oh, yeah, a reaction here would really help, explaining this a bit more here would be nice," etc. Or, sometimes it's bigger issues that, again, don't present themselves until you finally see it all cut together. It could be a fantastic movie overall but one or two sequences just feel a bit off, need better pacing, etc. Then there are also the rarer instances where a completely new idea presents itself after the fact, and now they want to go back, shoot it, and implement it. In other words, "reshoots" don't always mean "we screwed up." More often than not filmmakers just don't know what they truly have until they see those first edits, and reshoots have already been built in to the schedule to accommodate any final helpful touches.