I had the same problem as reported in the issue:
https://www.googlenestcommunity.com/t5/Nest-Thermostats/Solved-Password-has-changed-for-the-network-...
Clearly a few Nest Thermostats of the 3rd gen have this issue and unfortunately Google will not stand by their product as their support states:
2:04:34 PM Lois: But it is already out of warranty and can't see networks is not qualified for exception.
Without WiFi you cannot use it with the Nest App or subscribe to savings when it is remotly controlled.
So it is really insane that they do not see this as a qualified issue. My First Nest Learning Thermostat was installed in 2015 and still works. This one was installed in 2022.
On top of that the support than states you can purchase a new one from the Google Store but that is fault as they only sell the 4th Gen that will not work with the Nest App which is the only app I am using to control my Thermostats.
End result, I had to go to eBay and find a 3rd gen replacement unit.
Extremly unhappy with Google's attitude towards their loyal users (9+ years) of Nest Smarthome products.
