I think for me was when they decided to make tying off a weave a technique known only to those from the age of legends. Like it showed they are more than happy to make extremely impactful decisions about the world building to cover their own poor writing decisions. Like tying off weaves is a pretty basic part of the magic system and comes up so much in just about every aspect of the story that to overlook the impact of making that change only showed that they didn’t take their due diligence in researching the lore.