That suggests an issue with your speakers not having ‘clear’ access to the SiriusXM servers, and is more concerning if others are experiencing the same thing. Unfortunately, SiriusXM uses different servers for the Sonos content, so testing with their own app doesn’t hit the same data stream. Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it?
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.
Ot could also be a DNS issue between your area and the SiriusXM servers, but that does seem much less likely.
And if it is an issue with the data being fed to Sonos, they could contact SiriusXM and talk to them about the data stream from the server that is dedicated to the Sonos stream.