@Kyle Heath a direct answer: yes, you will be charged for 10k tasks (as long as those mapped tasks are successful and take longer than 1 second) because mapping generates first-class task run objects that work the same way as any other tasks and include their own retries, observability, etc.
an indirect answer: I wouldn’t view this as being priced per task really. You pay for the platform in general - the reason why pricing is based on the number of task runs is because this is a visible metric of Prefect adoption. As you run increasingly more tasks, you’ll probably also gain more and more value out of Prefect