At first I was thinking that maybe the artist of that poster simply made a mistake, however taking a closer look at the teaser, the poster looks accurate to how the Falcon is in ‘Solo’ (what a boring movie title).
There is one very vague line I’ve pointed a red arrow at that may be where the docking mandibles (as we know them) end and the compartment filling the gap between them starts which I guess means that it not only fills the gap but extends onto the end of the mandibles themselves to give this more angular design that doesn’t have the iconic snub / flat ended mandibles, something like the below example:
Val