after several weeks i got the following response from google, atleast it
appears to be a known issue and may get rectified in a future
updateThanks for reaching out to the Google Nest Customer Care Team.This
is XXXXX, from the Chromecast Support Team...
no responses anywhere from google, but it appears to be a common issue
popping up on multiple forums. one "fix" that seems to work is changing
your sound setting from Dolby Vision back to HDR. I tried yesterday and
so far I haven't had to restart.