Interesting. I know it involves a different sort of hitbox, but I used an iron club for the first time ever in A18 in my A18.3 save after the update, and found I had far more trouble hitting zeds than I'd had when using the wooden club. It hadn't occurred to me it could be related to the update...But I notice that a LOT of hitboxes are off now. Especially frustrating is the forge, workbench, and chem station.