Can you tell for sure it’s coming from the speaker?  I had the same issue with a certain bass frequency using an Arc.  Turned out the side panels of the TV stand were resonating.  I took 2 doorstop wedges and jamed them between the shelf and side panels.  One of those cheap audiophile tweaks.

Hey there thanks for the reply.  I’ll double check that by setting the speaker on the ground - pretty sure it’s coming from the left side of the speaker as far as I can tell. 

If you’re able to prove it is the speaker, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call 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.

If it is the playbar can you localize the sound to a particular driver?

Possibly use something like the cardboard tube in a roll of paper towels over your ear, kinda low tech but effective.

That’s for all the feedback guys.  Oddly I went back today at the time stamps on the episode I watched last night - and no more buzzing.. going to keep monitoring for if/when it comes back and marking down the time stamp/what episode I’m watching, for if/when I call support.  Super odd as I’ve been having this buzz issue for awhile and now it magically disappears now that I’ve started trouble shooting.. will keep y’all posted