Sure sounds like a Bluetooth issue. Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it? 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.
Frankly, it’s hard to guess whether this issue is with the Sonos receiving the Bluetooth, or your unspecified device sending it. I’d hope the diagnostic would contain some data pointing one way or the other. I’d certainly check the unspecified device for updates, as well as the Sonos, which for the headphones has to be done in the controller, as a specific action, if memory serves.
