Volume on SDR small TV doubles/halves

I have moved my old ATV 1st gen to the kitchen , where I have a small 1080p SDR TV. I was watching “Cheers” after a couple of other shows and one day, in the middle of season 1 after pressing pause and play again (not sure if I touched anything else by mistake) the volume halved. I must say that originally with Cheers the volume was a bit loud.

I couldn’t manage to fix it rebooting ATV, TV and so on. I raised the volume in the Audio configuration (50%-100%) but that option was syncing with my ATV 3rd gen connect to the Dolby AVR, and I don’t like it. Both ATVs are on tvOS17 last beta.

Once I thought to try playing a show with a big noise (gate opening in GoT, first scene). the volume in GoT was right and back to Cheers it sticked. Randomly the volume halves again, I use this workaround and Cheers goes back to normal (i.e. loud). Less frequently I believe, but it still happens.

Is it a bug? A bad stream?