Forgive my naivete, I am honestly curious how this fits with the Flat Earth hypothesis.
I have just concluded a long distance trip. I first flew from my hometown in Austin, TX, USA, into Riga, Latvia, in Europe, to visit a friend. I flew North-East from Austin to Chicago, then East across the ocean to Warsaw, Poland, then NE again to Riga. I stayed for a few months. Afterwards, I flew to Brisbane, Australia, to visit another mutual friend. I flew East, to Moscow, Russia, then South-East to Seoul, South Korea, and finally South to Brisbane. I stayed again for several months. Finally, I flew back to Austin. East to Fiji, then North-East across the ocean to Los Angeles, then South-East back to Austin, Texas.
During my flights, the time zones and position of the sun changed as I would expect if the earth were round. Also, I was in constant contact with people in all three locations (and also people in the UK, which is admittedly reasonably near Latvia.) These are all close friends I know personally. All of their daylight schedules varied as I would expect, with the people to my west experiencing daytime earlier, and people to the east experiencing it later.
If the surface of the earth is flat, how did I manage to travel only east and wind up back where I started? Also, how do different daylight times / time zones arise? Thanks for your consideration.