I contacted Ben at 9to5google and he wrote this:
https://9to5google.com/2022/01/21/nest-doorbell-camera-battery-cold-weather-reports/
Really hope Google answers!
I did it and they just wanted me to create a support ticket. Hope more
people will do the same to get Google to actually take it seriously...
This "monitoring" stage has gone on for way too long...
The infinity sign is shown even if the battery isn't full, I can almost
promise you that it hasn't charged at all for you, it just doesn't show
it. For me I had the infinity sign for weeks after charging it to full
and just one day it jumped to a cri...
Yeah the local AI and just thought it looked better. Also the
plastic/glass on the front had a crack, don't know why it got it. And
yeah, just thought a 3 year newer product would be much better and
faster etc. Overall the old one worked great though...