I’ve seen pics of a CF fork failing like this after a squirrel jumped into the wheel. While one might expect the spokes to cut the squirrel in two, the wiry little bastard stayed intact (but dead) and the fork gave way instead. Looks to me like something more substantial than a squirrel got into the wheel and started shearing off spokes. Every time the next spoke came up, the object was slammed into the back of the fork before the spoke failed. 6-8 broken spokes and 6-8 impacts against the fork later, it was the forks turn to fail. I would’ve said a stray tree branch, but a branch stout enough to do this damage would hardly be missed. Maybe a piece of metallic road flotsam, like a tool (wrench or screwdriver)?