According to Apple in 2019 Spotify didn't actually pay 30% on any of it's subscriptions at that time, and only paid the 15% on 0.5% of the App's users. The rest are ad supported and Apple gets 0% of the ad revenue.
So for every Spotify app user Apple get's a 15% fee for, there are 199 Spotify app users Apple is distributing the App to for which they get nothing.
https://www.cnet.com/news/apple-fires-back-spotify-pays-fees...
OK, that's the fact side of things. As for opinion, I think it's ridiculous that App vendors can't point out alternative payment options in their apps. That's a step too far. I'm also a bit concerned about digital sales, I can see why Epic doesn't want to pay 30% on every skin or loot box sold in Fortnite, but it's a free app otherwise distributed on the App Store for nothing so I think some sort of deal needs to be struck there.
Other than that, I think the iPhone is Apple's product. They get to decide how it works, and users get to decide whether that's acceptable or not. Apple (and NeXT) spent billions of dollars over many decades, taking huge commercial risks to build that platform. A decade ago we were constantly being told they were inevitably doomed and open always wins. Well no, some of us like the way Apple does things and don't want it to massively change. Some things sure, they're not perfect, but I do not support changes that would severely undermine the integrity of their product. You can always buy an Android phone.