The original Nest thermostat and app has been abandonware since 2017, as far as I can tell. We got one in 2014, and I can only remember one change. A couple years into my use of it, the iPhone X came out, with the notch and taller screen. The Nest app eventually got updated to fill the whole screen, and that's it.

To be fair, I can't imagine why an app for a thermostat would need regular updates - aside from what's necessary to keep the app functional on modern OS versions.