Executive Meddling: After Mark Millar took over, either DC or Wildstorm began demanding and forcing constant changes. This reached its peak with the "Brave New World" arc, where the arc was actually sidetracked for four months for the "Transfer of Power" arc (which pissed Millar off to no end, because by the time he was given the series back, 9/11 happened, creating a pretense for the executives to put the book on hiatus and force him and Art Adams to make even further changes.) To be fair to the executives, Millar was not easy to work with, constantly attempting to push the limits of what was permissible for a CCA-approved series (had the executives not intervened, "Brave New World would have featured references to the rape of Jenny Sparks' corpse, and a scene in which Swift's "husband" uses her mouth as an ashtray in a deliberately-sexualized manner, among other potentially offensive content) and often injecting his political views into the series.
The latest trade collection of Millar's run featured some of the original artwork Adams created in place of the edited version initially used.
Unfinished Episode: Rumor has it that had Mark Millar not defected to Marvel Comics, there would have been one more arc in which the team battles against Jesus Christ.
Trend Killer: It's generally agreed that The Authority and the vitriol it created killed the use of authority figures in wrestling (which ironically had Vince McMahon as one of those who popularized it), or at least ensured they would never again be the main angle. Notably, when Adam Pearce and Sonya Deville became the de facto authority figures of Raw and SmackDown after they began booking matches in late 2020, they were simply referred to as "WWE Officials", and even when Deville started a storyline with Naomi that saw Deville as the heel, it was definitely far from being the main angle- plus, said angle actually had a payoff with Deville being stripped of her position for misusing her powers.
