It's so weird. The truth may be that both might be right.
The earth might be MUCH bigger than previously thought, which gives the flat earthers correct data (About its flatness), and that the earth really is spherical, which causes the phases of the moon, and the rise and sun of the ... well you know.
I really don't know, but it is surely fun to investigate.
“The earth might be MUCH bigger than previously thought...”
Well, Erastothenes was able to make a quite accurate estimate of the diameter of the earth over 2000 years ago with very simple methodology. That’s really not an area of science that is very debatable at this point.