It may seem that is not entirely flat but it may be because of how both lateral sides are curved that gives you that illusion. In other sequences of the video i have the impression that the angle is not really 180° but those details are really littleness expecially when comparing it to huawei foldable phone that really is folded upwards after being opened and not really in a clean way. I don't know why this jack is so important that everyone have to sink any phone that doesn't have it. OF course it may be an hassle for someone who was used it but you have to with wireless headphones or similar. I wasn't impressed seeing the Galaxy f only by images but after this video i think it could be very practical considering the flowing form of the curves that could fit really well in hand and pockets. The form once closed seems ergonomic, once opened efficient and pleasingwhen browsing, the overall assembly very premium. However i don't think this may be the very best project of a foldable phone, seems overcomplicated but in the end not confused and twisted like i previously thought they would make it, like the huawei foldable is (imo)