Yeah, that it exactly what is happening, but it's not Spotify's fault. What spotify and other music apps want is the default behavior of Apple's music services. The device has a strangle hold on the volume and no API allowing good software sound control. Spotify can't force the device to do something that Apple forbids in order to force project their own music service onto users.
Meanwhile, in the other OS, we already have a desktop like sound mixer including multiple output control and per app control. iOS is a worse bad joke every day. Second only to Windows.
Spotify blames the change on Apple, saying the company won’t give it access to the same technology that lets Apple Music play on third-party devices. As a result, controlling volume with the iPhone’s physical toggle has “become unstable” for connected devices, causing volume to spike during playback and other bugs. Spotify says the change will result in “persistent, high-quality” volume control. The Sonos app has also stoppedletting iPhone users change the volume of their devices using physical buttons for similar reasons.
Apple runs their own music streaming services, too, no? They obviously can't come right out and ban a service that so many people love, the backlash would be insane, but they can slowly, very quietly, make it difficult for competitors to deliver good products to the market (the same market they control).
I believe Spotify here, from personal experience, the os suddenly decides to spike the keyboard clicking sounds to maximum volume out of the blue without playing any other audio at the time.