Just bought Sonos Arc Ultra yesterday. First movie a piercing sound started.

About 30 minutes into Top Gun movie the Sonos soundbar started making this loud piercing sound. I shut it down for about an hour, then put another movie on. Towards the end of the second movie the piercing sound came back. I opened a ticket with Sonos through chat last night and sent them diagnostics. They said nothing abnormal. I have limited time to return this thing to Amazon and right now I am ready to send it back. What could be causing this? The TV has ARC output, Roku feeds the TV. Brand new HDMI cable going to TV that came with Sonos. I don’t see how to attach a non URL video to this post, else I would attach the video I took.