At the risk of this being a post hoc error, my crafter's Master Writ drops have dropped off to almost zero over the past couple of weeks (since the end of Anniversary). The only thing which has changed is that they now know all 135 motifs as I went out and bought the last dozen or so chapters they needed around the end of Anniversary. Consumable writs and Jewelry writs have been dropping normally for them, but Blacksmithing, Clothing, and Woodworking have almost dried up completely. They got 1 Woodworking writ a few days ago, which is pretty close to what I've seen with characters whose drop rates are based solely on trait knowledge and whatever Motifs 11-14 might add to the drop chance. I cannot say with any degree of confidence that this is U49-related because I have no point of comparison prior to U49 with the same conditions and RNG can be a real beast sometimes, but a couple of weeks worth of writs failing to drop more than 1 or 2 gear Master Writs on a character who should have the highest drop chances possible is odd enough to warrant a "something seems fishy about this" post.