I am also in the public preview program, and I have found ultrasound
sensing to be the issue. This happened to me a couple of years ago, and
popping hasn't returned after turning off ultrasound sensing since then.
Just FYI
I have found it to be the cause - I had this problem quite a long time
ago (2 years maybe) and found it doesn't pop when ultrasound sensing is
off. Sorry about that!
I found the problem - the reason this is happening is due to ultrasound
sensing being turned on. To turn this off, click on your speaker in the
Google Home app, then click the Settings icon in the top right, then
Recognition and sharing, then turn of...