People keep saying Kinberg is lying, but they're not thinking like writers, in terms of structure and story.
After the reception of APOCALYPSE, it's unlikely the movie would have been longer than say, 2:15-2:20. We started hearing that they intended to make a smaller, more intimate film almost immediately after the reception to the previous one.
There's clearly a focus on Phoenix herself this time around, and there are already a number of other storylines to develop and potentially wrap up, and there just likely wasn't ever going to be a sudden focus on Xavier's interstellar romantic life (Moira hardly counts) and a full introduction of the Shi'ar in the main narrative.
It's far more likely that any falsehoods being told are in regard to what was changed about the third act. Because I'm sure "wrapping up the franchise" had to be a major consideration of whatever reshoots occurred, and that they didn't just alter a space sequence for the heck of it, but more likely because that particular space sequence was designed and intended to send the franchise in a new direction, at least for one more film.
If there was a massive twist, it was likely something cosmic that would blow the franchise up again and make it more cosmic for a potential Part II scenario. Given all the rumors, it's quite possible there were some kind of Brood/Skrulls stand ins earlier in the film that were intended to lead into the Shi'ar's involvement in the universe along with the evolution/resolution of Phoenix.
