Apparently, the actor's plans were set in stone for a while. According to Deadline, her brief appearance is due to continued filming on the forthcoming second film in the Dune film series.
That said! This latest development only adds more fuel to the fire that is the Don't Worry Darling press cycle, which has at times centered around rumors of a feud between Florence and Olivia.
After Olivia had hyped up the film's sex scenes, Florence expressed her distaste for excessively talking about the film's sex scenes. “When it’s reduced to your sex scenes, or to watch the most famous man in the world go down on someone, it’s not why we do it. It’s not why I’m in this industry,” she told Harper's Bazaar.
Amidst all this, Florence hasn't really done too much press for the film, perhaps signaling a wish to distance herself from Olivia and the experience as a whole.
And whether or not skipping the Venice press conference has anything to do with the ensuing drama, it's certainly hard not to draw conclusions on one's own. Time will tell!