I don’t use a Firestick, but it sure sounds like it’s messing with your TV. Have you checked for updated firmware for the Firestick?
There’s been many issues reported around some types (and not being a user, I’m not sure which versions) that suggest that the Firestick is fighting with the TV’s CEC computer for the “audio sink” concept, I’d probably want to try one of those Lindy CEC blocking adapters in between the Firestick and the TV set.
But firestick was all good until Sonos Amp was connected to HDMI ARC port on TV. It does sound like their is a “fight’ going on though. I saw some other posts that mentioned the need for a HDMI cable with ethernet. I had an old HDMI cable and swapped it out today for a “with ethernet” one and it hasn’t glitched since. Fingers crossed and I will close this thread if it lasts until tomorrow. Thanks for your input.
It lasted, but then started happening again, just not as frequently.