When using the API to communicate with a Nest Learning Thermostat (in this case using the nest home assistant integration), when a request is made to change the nest thermostat to the "OFF" mode, I can see the mode show as "OFF" on the home.nest.com website, however the thermostat doesn't register it at all and just stays in whatever mode it was already in. Curiously, when I select "OFF" on the home.nest.com site the OFF mode that's displayed on the site has a leaf icon under it, while when I do it via the API it does not. When selecting it on the site the thermostat does switch to "OFF" with a leaf icon displayed under that on the thermostat as well. It seems like the API is sending an "OFF" state that the home.nest.com site can see but that the thermostat itself just doesn't respond to at all for whatever reason. It's like there are two different off commands here and only one of them (whatever the nest.home.com site is using) is working, and whatever the API is using is not. Seems like a bug but I wasn't sure if I'm just doing something wrong here or what. Just wanted to mention it here so that it will hopefully have some visibility from the devs. Thanks.
API bug confirmed, seems to be fixed here: https://github.com/home-assistant/core/issues/60941