Toggle the HomePod autoplay feature

HomePod includes an autoplay feature which when enable should play similar content to song, album, playlist, etc. that was originally selected when it ends. This is similar to asking Siri to "play more like this". The option might be unexpectedly enabled following a HomePod update.

Open the Home app on your iOS device and use a long press on your HomePod to access it.

You should see artwork for the currently playing or paused item below which is a Now Playing area, tap this.

Underneath the currently playing track will be a Playing Next section. Tap the infinity icon ∞ to turn autoplay on or off.

For more on this feature see Add music to your queue to play next on your iPhone, iPad, iPod touch, or Android device - Apple Support.