I am having the same problem with my Nest Hello doorbell, which randomly started doing that in January. I have 3 other Nest Outdoor cameras which are fine and do not do this. Google Support originally told me it was a problem with the doorbell transformer, so I had an electrician replace everything except the Nest Doorbell (including the chime connector in the chime box). NOPE! It still goes on and offline. He concluded the doorbell unit itself must be failing and said to contact Nest Support.
I spent over 2 hours on the phone yesterday with Nest Support, who is determined to blame it on anything except the Nest Doorbell. They made me repeat every thing we've already done to fix the problem, and it's still not resolved and supposedly escalated up to engineering. 🙄 They want to blame my WiFi network (which is also Google mesh), but no other camera or any other device on my network is having this problem. My network is fine. Seriously, I spent over an hour with a Level 1 support person, sending screenshots to prove my freakin' WiFi network is FINE, solid high-speed internet connection, etc. before they escalated it to a "senior" support person, who then repeated everything I just did before giving up and saying they had to escalate to engineering.
Anyway, that's the experience you can expect if you're forced to actually open a ticket with Google Support. Their support people only know how to follow a script and have no real ability to think about a problem critically.
Here's a screenshot of what's happening on my doorbell camera. Are you seeing the same type of pattern on your outdoor cameras? I'm wondering if they have pushed a firmware update or something and torched something in the cameras/doorbells.
