When you retrieve the RSS feed for the podcast, your client sends its name in the header just like a browser.

Spotify is at 10%

https://a16z.com/2019/05/23/podcast-ecosystem-investing-2019...

Spotify "caches" episodes so it's clout tends to not be actively reflected in such numbers.[1] I don't know how much but I can assure you it's way higher than 10%

https://www.reddit.com/r/podcasting/comments/9ytna1/does_spo...

If that’s the case, it doesn’t help podcasters. Podcasters get paid based on number of listeners. If the podcaster can’t count Spotify users, they are not as valuable to podcasters.

However, Overcast also caches RSS feeds but it does send the number of subscribers for a feed in the header of the GET request. It also doesn’t cache the actual audio.

Once you put your podcast onto Spotify they give you better info on your listeners and subscribers and number of listens (at least the ones listening on Spotify). You don't lack any data.

We've refused to put any of our 8 podcasts on Spotify for various reasons. One of the reasons is that they will accept money from paying customers and from ad co's for non-paying listeners, but simply want our content for free. Ummm... no thanks.

Additionally, Spotify has older podcasts ‘marked’ on where the audio ads go, and will serve an updated audio ad within the podcast, even though the episode may be several years old.

Could this be Spotify’s version of AdWords for audio?

You can already get dynamically inserted ads with podcasts without going exclusively Spotify. https://marketingland.com/your-quick-start-guide-to-podcast-...