While it’s certainly great news that J.K. Simmons and, apparently, everyone else who appeared in Justice League is looking forward to seeing and being in Zack Snyder’s cut of the film, the word going around says that no reshoots will be necessary. Supposedly, Snyder wanted to shoot some additional bits for the film, but in order for HBO Max to agree to financially support his cut at all, they wouldn’t allow for anything as extreme as actual reshoots. Instead, the new streamer was on board with offering money for post-production, special effects, scoring, and even some ADR to add / change dialogue, but that was it.
Article source: https://www.cinemablend.com/news/2549994/snyder-cut-justice-leagues-jk-simmons-is-ready-for-reshoots-if-zack-snyder-calls