When did paid podcasts become a thing?

Half the podcasts in my queue have suddenly become paid subscriptions. Meanwhile the overall industry is losing listeners. Seems like a lousy business model to not offer a free with ads feed. What a bizarre trend.

https://www.deseret.com/entertainment/2023/2/9/23592684/decline-of-podcasts#:~:text=Monthly%20listenership%20to%20podcasts%20seems,podcasts%20has%20fallen%20as%20well.

https://www.marketingbrew.com/stories/2022/03/28/monthly-podcast-listening-is-down-for-the-first-time-in-almost-a-decade-according-to-study