If it's obvious to anyone with a telescope, that at least Jupiter is a sphere, why would Earth be flat?
One answer I hear from flat earthers is that other planets are round, but not Earth.
The other answer is that space is some sort of projection, and you're not seeing planets are all.
If Jupiter is flat or a projection, the big red spot on that projection, disappears over the edge, then reappears from the opposite edge, and moves slowly across the face.
So you're saying the night sky is a projection?