Prime Video Shows Ads During Movies and Series Without Warning Me

I was a Prime Video member before, and I renewed my membership again. Then I encountered something ridiculous. When I open and start watching a series or movie, an advertisement pops up, especially a video promoting Turkish series on TV. Now I have a question for you: why wasn't it mentioned when subscribing that "Dear user, we will now show advertisements on the content you watch?" If I had known this, I wouldn't have renewed my subscription. I wrote to customer service, and the woman I talked to was surprised; she didn't know about this either. This is unfortunately misleading people. I'm waiting for an explanation, and I will cancel my subscription from now on.