There are multiple threads about audio drop issues and tvOS 17... particularly involving eArc flows of audio through TVs to sound systems. I've seen enough varying situation posts to believe there is probably something buggy (new) in tvOS 17. This is definitely not an isolated issue.
OP, if you are able (and this guess applies), perhaps try re-wiring the audio flow from AppleTV to TV to soundbar/amp/receiver to AppleTV to soundbar/amp/receiver to TV. Of course, this can't necessarily work for everyone, particularly soundbar people with only a single HDMI input for eArc.
If your TV happens to be a Samsung TV, there are at least a few threads specifically singling out these kinds of audio issues when flowing sound through Samsung TVs. It think the want there is to fault Samsung but the variety of models and that all was fine before tvOS 17 doesn't rule out AppleTV and/or tvOS itself.
If you have another source of A/V, I suggest temporarily connecting it through the same cable used with your AppleTV to see if Audio will be fine from the other source(s)... even better if you can play the very same kinds & formats of video. That would help narrow this in on AppleTV or tvOS by ruling out the usual "blame everything else first" help.
If a specific video or two ALWAYS has audio issues, copy it to a drive and then use a audio source (Mac?) able to play from that drive through the same cable connection used by the AppleTV. If it plays fine that way, think about the only variables that are still different.
