I have 4 Nest outdoor cams, and a Nest Hello, and all have this issue. When viewing live, or a recorded clip in the Nest app, there is no audio on the phone. This is with a Samsung Galaxy S10, and both the phone's software and the app is up to date.
I saw another post from earlier this year about the same issue that was closed with no resolution. This is too important of an issue for Google to just push aside!
I apologize for my late response and thank you for all of your patience while waiting for a reply. I definitely understand how frustrating your situation must be, and I wanted to make sure that your concern was acknowledged. Do you still need help with this issue? I know that there's been a delay in response since you posted.
Just checking in to see if you still need assistance with this issue. We'll leave this topic open for another 24 hrs in case there are any follow up questions or comments. Please let me know if you need further assistance.