Ah that's why my Nest Thermostat is not showing up in Home Assistant. Great design Google, thanx, hooray for the cloud.

(Edit: Nest app does work :s, why must it be like this.)

(Edit2: I also did upgrade Home Assistant this morning, that could also be the cause, I'll have to figure it out. That's really a downside as well, you always have to ask, is it me or "the cloud" [my computer or someone else's!]. I wish the cloud was not a factor.)

(Edit3: Nest integration works again after a restart of the HA container)