Tried that with Arc-Sub-300s.  Grouped with Move Stereo pair & Port.  No change in TV sound.

 Am on 80.09.09.  I would think for a issue like you describe to occur it would likely be due to a firmware change and not an app change.

 I don’t do that grouping when playing TV sound due to dropouts from the grouped speakers.  The dropouts do NOT occur with music.

Thx MoPac for yr feedback.

Checked some other settings in the Sonos app.

In the Home Cinema section, I switched off the Synchronise TV dialog setting and decreased it to 0 (from 4)

The distortion is now gone and the grouped sets of speakers work perfectly as before the update 2 days ago.

i’ve never touched this setting before, so Sonos has apparently changed something in release 80.09.09. 

Thx again

 That’s weird!  Checked my Synchronize TV dialogue setting.  It was at 0.  Never fiddled with that setting.  Thanks for the warning.  Guess I’ll leave it alone.

In the mean time I have changed the dialog setting from 0 into 2 as the dialog of set #2 was annoyingly lagging behind set #1. With setting on 2, the grouped sets are (for this moment) nicely in sync.

With Sonos S2 these days, you’ll never know for how long the bloody app keeps working w/o hiccups, sudden never before encountered issues etc, etc.

Have a good one

You might read  up on Sonos lingo. I see you using “group” where you seem to mean “room”, but you seem to up use it for what Sonos does call a group too. This is confusing, especially when speakers that are grouped with a home cinema set can have a delay, while speaker in room forming such a set should not have a delay.

 You’re right about the terminology.  My “bonded” HT room when “grouped” with other rooms while playing TV sound suffer from issues.  There is a delay and some intermittent dropouts on the speakers that are grouped with the HT room.  A while back I tried listening to the news while eating dinner in the kitchen.  i was grouping a pair of Move speakers for that task.  The dropouts were too irritating so I gave up that idea.  This does not occur in the group when playing music.

 The Synchronize TV Dialog setting can be changed if it looks like the HT room sound is not matching the lip movement of the folks on the TV.  I don’t think that setting is used to try to synchronize with a room grouped to a HT room.  @brave855 proved that doesn’t work too well.

https://www.reddit.com/r/sonos/comments/sfwkma/tv_audio_stuttering_when_grouped/
 

I ve never ever experienced this in my 2 rooms with 2 “bonded” sets of speakers grouped with 2 volume sliders for each set so conclude it must be a “glitch” in IOS 80.09.09

The “solution” described in reddit also does not solve the issue flagged in this thread. 
 

sonos app remains messy, with in every new update, new never before encountered (annoying) surprises

After upgrade to 80.09.09, my iPhone 16 Pro couldn’t find my existing system, although it was present in the desktop app. Same with my wife’s iPhone 16. After power off/on cycle, it was able to find my existing system.