It seems that this "Tartaria" narrative is also false for the most part, possibly a psyop to muddy the waters (similar to "flat earth").
There are some mysteries raised by its proponents that seem legitimate, eg. the early World Fairs constructions, but the overall idea of a forgotten advanced civilization just a few hundred years ago seems to be a psyop to misdirect people from topics like ancient cataclysms, Atlantean civilization, phantom years, etc.