Thanks for posting about this on our Community!
We'll be happy to explain a bit more about this. Spotify gives the podcast hosts the option to choose if they would like to have a dynamic ad slot in their podcast.
You can find more info on this here. We understand that many of the creators that you're listening to seem to be using that option but that is not something Spotify can control - it's up to the individual podcast owners if they choose to have that type of ad in their content.
We see that you have posted an idea about changing that and it's marked as new which means that people can vote for it and show their support.
You can learn more about how ideas reach the right teams here.
Hope this explains the situation. We'll be here if you have any other questions.