If there was a separate box or better, a popup modal/page, that explains this, I'd give Adobe the benefit of the doubt.
The problem is patterning - _a lot_ other companies monthly subscriptions don't have 50% annual cancellation fee or any cancellation fee. So this method of 'lowering the price' is uncommon/against-the-grain.
When faced with an uncommon situation you really need people to understand what they're getting into, otherwise lots of people are surprised when they get hit with this.