Why would the moon looking a certain way prove the shape of the Earth? This makes no sense to me. If it is unside down or right side up, or a hologram, or a big rock. How does that prove the Earth is round? No one really knows what the moon is anyway, unless you believe tha moon landing stuff they made up to "win" the space race against the Russians.
If the earth was flat then the moon would look the same way up whether you were north or south of the equator. Of course it's not the moon that appears upside down, it's the observer. Even if the moon is a hologram or whatever you think it is, this still disproves the flat earth. ( I expect Jrowe will chime at this point in with his dual earth variant )
Unless there was some kind of brain implant inserted to everyone at birth, keyed to a gps system to correctly display the moon hologram.
As you dig deeper into flat earth theory, you will find that it completely fails to describe what happens south of the equator.
1. The stars in the southern hemisphere revolve around the south celestial pole. This means the earth has two poles.
2. Distances in the southern hemisphere can't be measured on a flat earth, because there is no flat earth map that works.
And on it goes, not a single argument for the flat earth holds up to any kind of critical scrutiny.
But, that said, you meet interesting people and it's never a waste of time to critically question everything.