No, it doesn’t make sense at all, in lots of ways. Where your controller is running, for instance. It is merely a remote control, telling the computer in the speaker where to get content from and allow it to play. Once you’ve told your Sonos to “play this stream”, you can shut down the controller, and that stream will continue, because it is the speakers that are doing the heavy lifting, not the controller.
Which is all fine and good, but doesn’t really explain why you would be getting any encoding errors when playing a Sonos Radio stream. It certainly has nothing to do with Apple, or DRM. What I suspect is happening is your speakers are getting corrupt data from the source, and reporting that (poorly) as bad encoding. I’d try several things. First, I’d reboot the router, then the speakers themselves. If that didn’t fix it, I would submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.