I knew about the Flat Earth Society decades ago, used to think it was a Monty Python type club, just to show one was a nonconformist. When the recent fluorescence of flat earth started a few years back, as a collector of eclectica I thought perhaps I had missed some good info in my researches. Was stunned to run smack dab into a psyop-fueled retardation fest. Lost a few friends along that way. I came to realise that researching flat earth is a neurological study, not geodetic. However, I do understand the state of "awakening" that they are talking about, as I experienced that long ago, the infinite higher anthropic plane of life, which just happens to be wrapped around a giant spherical planet. It's the confusion between that inner state of awareness, which one must have their inner landscape in order to experience properly so they don't get lost, and the objective structure requisite to holding that state.
This is just a small piece of a larger writing project on the different world views, so I will be covering that in detail in time.
And yes, expansion tectonics is an important clue. Have a look into the potentially related "Canopy Theory", first promoted by Isaac Newton Vail in his Waters Above the Firmament https://archive.org/details/watersabovefirm00vailgoog ... you'll find much more searching the web, pro and con, the Biblical Creationists love this one. Could help explain the apparent gravity-variant effects on flora and fauna.

Definitely more to come in this vein. I'm an anthropocentrist, all of these pieces fit a larger puzzle, the concepts of which are not amenable to sound bite transmission ... or hypno-meme programming :) ... One needs to construct larger frameworks in consciousness to start seeing it. I thank Ernst Lehrs, his book Man or Matter introduced me to the Goethean method of cognising the processes of manifestation.
http://borderlandresearch.com/book/man-or-matter