Well, this explains a lot. Despite grossing over $600 million at the worldwide box office, Justice League was still considered a disappointment by Warner Bros. and it appears as if expensive reshoots weren't the only reason. Despite Justice League: Part Two being put on hold fairly early on during production, it seems as if Zack Snyder was intent on shooting a BIG movie.
During an appearance at the Heroes and Villains Fan Fest in New Jersey, Cyborg actor Ray Fisher was asked about what the future holds in store for Victor Stone/Cyborg and while he clearly has no idea, he made it clear that there's more than just a handful of scenes on the cutting room floor which were shot by Snyder.
"[What] I will say is Zack had very specific plans for Cyborg, and for his trajectory. And Zack probably shot enough footage in the first film to make like two movies out of. He definitely had a whole, I believe, a trilogy in mind, with respect to Justice League. And if his vision had sort of come to fruition, Cyborg would have probably been one of, if not the most powerful, metahuman in the entire canon, in the film universe. And that’s just one of the crazy things about Zack, is that he can take someone who’s such a newcomer and evolve their powers to the point where, you know, Cyborg is like 'S tier.'"
This is interesting for a lot of reasons; for starters, it seems as if Snyder was shooting footage which he would have used further down the line and, if not, having what was probably a four-hour assembly cut of the movie just goes to show that the budget must have ballooned out of control long before Joss Whedon was hired.
Cyborg becoming the most powerful metahuman in the DC Films Universe also would have been quite something and it's starting to make sense why Warner Bros. initially had plans for a solo movie.