I like going back to old theories after Archon quests to see what people got right. Before Sumeru was released, a big theory that always came up was that basing on the Travail trailer, the Dendro archon would be spreading misinformation to protect her people and prevent them from suffering the same fate as Orobashi when he read the Before Sun and Moon. The theory said that this is the reason why "the god of wisdom's enemy is wisdom itself" and why "there's a push for folly" but the Dendro archon seemed not to care about it.

Really, there was misinformation but it was the Akademiya spreading it, not the Archon, and it was to further divide the country, not to protect it. And the wisdom that's the God of Wisdom's enemy is actually the forbidden knowledge that polluted the Irminsul tree and the dreams that the Sages used to create a god to replace her.

What are theories you liked but got debunked later on after a quest?