Quote from Auric245524
Then enchantments on a focus make an effect in crafting too. Potency will increase the cost and frugal will reduce it. Unless the focus you had was unenchanted, it's not a bug.
Really? Well that's interesting to know. Looking back at the focus I had equipped, it does have Potency III on it which explains that added vis usage. Guess I'll be crafting with my Frugal III focus of dislocation from now on!