How do I stop my iPhone playing when using Homepod

Again, it isn't playing through the phone. The phone is merely providing an additional means of control that you could use, if you wish to. Right now I've just used my phone to raise the volume slightly on my HomePod without have to get up and walk over to it, or interrupt the music by asking Siri to set a new volume.

If you think it should be possible to disable this feature then have your say at Feedback - HomePod - Apple.

tt2

Did you hold your phone near the HomePod. You might have Handoff enabled. See: Play audio on HomePod using an iOS or iPadOS device - Apple Support

Otherwise you’re seeing the controls show up on your iPhone Lock Screen and think it’s also playing on that?

When your iPhone is on the same network as your HomePod and the HomePod is playing content the iPhone can become a remote control for the HomePod, allowing you to pause playback, adjust volume, fast forward, rewind, or even select new content to play.

tt2

The HomePod is playing on its own. Kick the iPhone into Airplane Mode to prove it. The volume control in control centre will act as a remote control for HomePod if the iPhone isn't playing anything independently itself. This isn't a feature you can disable.

tt2

You're welcome. 🙂

tt2

You might find yourself liking this feature. I didn’t like it at first and it not only shows up on my phone but my iPads as well. I really like it now though.