If the music audio output sounds like it did before and the issue you are seeing only applies to the TV audio, then maybe roll-back the TV firmware update if all was well beforehand (that’s if you have access to the previous build on USB stick, or via manufacturers website?) or maybe speak to the TV manufacturers support desk and see what they can suggest.

It seems ‘unlikely’ that it’s going to be the Sonos product if all was previously working okay and the TV audio output is the only thing that has changed since performing the update. 

Thank you