Stripe

Stripe is a great product but also employs a massive dark pattern. It's almost impossible to know how much you pay monthly to use Stripe. There are bunch of reports you can try to download to analyze fees, but as you turn on their additional services (Revenue Recognition, Sigma, etc) it's basically impossible to see a breakdown of what you're paying. If people easily saw what they paid Stripe monthly (spoiler alert, it's a lot), I bet Stripe would have more competitors.