Everyone on Earth observes the same face and phase of the Moon at the same time, provided the Moon is visible from the location of the observer. This fact is contrary to what the flat Earth model requires. It rules out the possibility of a flat-Earth and that the Moon is a sphere hovering a few thousand miles above Earth’s surface.
If the Moon is as close as described in the flat Earth model, the appearance of the Moon will be different on the different locations on Earth. The Moon will appear to have a different phase, and an observer on the other side of the world will see the different side of the Moon.
In reality, the Earth is a sphere, and the Moon is far away, about 30 times Earth’s diameter. It is the reason every one of us sees the same phase and face of the Moon no matter where we are on Earth, provided the Moon is visible from our location.