Is there actually a command to turn up the volume (or a sign on screen that says so) or do you experience a higher volume?

That’s a pretty common broadcast trick, even across the air, not just on Hulu. Ads tend to be compressed more, and then broadcast at their maximum level. It’s not just an issue with Sonos, it’s an issue with the broadcasters and the way they treat advertisements. 

It’s not just during the commercial. The sound gets louder during the commercial and then gets even louder during still after the commercial. I understand it may be compression. It may also be something with LGs or LGs+Hulu+Sonos. It doesn’t happen with other streaming platforms or over-the-air/antenna broadcasts. My guess is that it’s Hulu related. I’m just fishing. The volume increases are deafening. 

Wait for it to happen and quickly send in a diagnostic, that will give you a number that you can give to Sonos support and have them look at your internal (hidden from us users) data and see if they can see what is fiddling the volume settings or if it is another issue.

I’ll try that Stanley. Thanks.