The ads are only for the free and $8/month plans. They basically added an ad-supported super discount level that you can ignore if you’re paying for the normal plans.

But the fact that they've added an ad-supported tier this early into their life as a company means they're desperate for revenue. You start inserting ads when you're optimizing for profit, not when you're still growing. It took how long for Netflix to introduce an ad-supported plan?