I would also include deceptive credits systems used by SaaS which have usage-based like subscriptions. It’s a bait and switch variant. First, you think one call to the API is one credit but it always turns out that you need calls which consume 20 or 50 credits instead and you have to move to a more expensive plan and buy millions of credits every month. Second, unused credits do not roll over to the next month so your effective cost per call is orders of magnitude larger compared to what you expected.