yeah, the flat earth shit completely fails because it disregards finite and unbounded geometries. only a naive idiot would think that just because the rotation of the moon maintains the same face towards us at all times means that the moon is flat, when it has a shadow that exactly matches what you'd see with a ball lit from one direction, walking around it. just make the ball keep facing you and there you have it. the light is moving around but the face is not.
another data point to this you can observe for yourself by looking at a *flat* mirror. when you get up really close to it, you start to notice that your face kinda distorts like your nose and cheeks get bigger and you can't see so much of your ears and side of your head. same reason. lenses, also, are shaped as the intersection of two spheres, and cause light to spread out or spread in. you can get the opposite effect with a concave lens, which is like a section of the difference of two spheres.
haha anyhow. yeah, i'm pretty sure that mainstream astrophysics doesn't assert that space is a finite but unbounded volume, a hypersphere.
the instant implication of this is that there is probably a horizon, but if the universe happens to also be growing, at the rate that we call light speed, at that point where the relative motion of space increasing between two points will create a black void, the 3d horizon. but if the universe is not expanding, then we would zoom in and see the old version of the universe.
i personally think that the universe is expanding, and that this is the base of almost everything else, but specifically gravity, which means that at some point James Webb or some later space telescope will discover a black void instead of the endless field of galaxies it currently sees.