I don't think the flat earth stuff is remotely the least bit credible.
e.g. people have flown--in steps & likely otherwise--totally around the globe from east to west and from west to east ending up back where they started.
Haven't kept up with "audodidactic channels" issues and don't know what "made up history" you might be referring to.
I've always tended to self-educate way above & beyond what happened in classes. I think that is a basic civic & personal responsibility
As has been repeatedly noted, the victors tend to write the history.
Those two channels talk about around 1,000 years of our recent history was added. There was Tartaria, a worldwide civilization that suffered catastrophe and there was a reset fairly recently. Within the last couple of centuries. The mud flood, etc. Not about flat earth but more this is a holograph we live in and they change things all the time.
Who really built the starforts and other buildings with the same style but there is very little documentation. Empty cities with great buildings but very little in matching infrastructure. Giants still living last century.
But all reset now.