Is this from the update today, or is it an older version of S2?

From both unfortunately.  I thought today’s update might fix it, but no luck 

Well, since they don’t bother to tell us what the new controller fixes, it was just a hope. I’d be tempted, in your shoes, to delete the controller from the iPhone, then do a hard reboot (power cycle) of the iPhone. Then download a fresh copy from the Apple store, and be sure to click on ‘connect to existing system’ when prompted. Then, of corpus’s, test. If it’s still having this same issue, I’d certainly recommend providing Sonos some hard data by submitting a diagnostic. It’s possible they can’t recreate the issue, just like me, and some hard data might prove usedpful to the programmer who would be assigned to look in to it. It’s hard to trace bugs with just anecdotal information, generally, especially if it isn’t affecting everyone. 

I’ve disabled the Lock Screen Controls and this workaround seems to have fixed my battery issue.  I’ll check my battery usage in a few hours.

Disabling the “Lock Screen Controls” has fixed my battery draining issue.

One has to wonder if this isn’t a Sonos issue, based on this report:

https://9to5mac.com/2020/07/08/apple-music-battery-drain/

I’d assume the Sonos app uses a standard call to the iOS system for use of lock screen controls. Conjecture, mind you, but the parts fit together. 

Thanks for the info Bruce.  It’s definitely an IOS bug.  I am experiencing the same behavior (battery drain ) when I stopped playing music with Spotify.

Yea, I’m not 100% certain either way, but found it an interesting read last night after reading your post yesterday. I tend to not use the lock screen controls when using Sonos, but was using AirPlay 2 yesterday, and I think it drained a bit more than expected on my iPhone X. But didn’t really check, either.

But as a non-programmer, with only familiarity, not real knowledge, it seems likely to me that Sonos is just attaching to an Apple API to create the lock screen controls, which made it possible that it’s more of an Apple issue. 

Found an interesting link: https://www.zdnet.com/article/apple-music-causing-big-iphone-battery-problems-heres-a-fix/

I applied the recommended fix by deleting the Music app from my iPhone and it did resolve my battery issue.  This workaround is, however,  not possible for Apple Music subscribers.