Sending the ThermostatEco.SetMode command appears to succeed, but the command either never makes it to or is ignored by the thermostat.
This happens whether trying to set eco mode to either MANUAL_ECO or NONE.
The thermostat eco mode can be changed using the device, using schedules, successfully using auto-away, using the Google Home app, and using the Nest app.
This used to work and nothing has changed on my side.
Has there been a change in the API or permissions required? Why are Google's apps able to change the mode but not my own using the SDM API?
Please see this thread for further reports of failure: https://github.com/home-assistant/core/issues/90619
Google Public Issue Tracker link: https://issuetracker.google.com/issues/288913306
Google have resolved the issue now. https://issuetracker.google.com/issues/288913306