That is not correct, it's only automatic if the thermostat was acquired
from your local gas/energy company. Otherwise you have to purposely opt
in. Retail units do not automatically opt into the program.
From the article, it was opt-in. "Some Texans have been sounding off on
social media saying their smart thermostats have been adjusting
themselves during ERCOT's call for conservation. Turns out it’s true,
and you gave permission."
Link? All my searches say it's opt-in, but I could be wrong. Retail
thermostats with smart features are not normally opted in. And the OP
doesn't mention what state they are from so may not be relevant.
Not entirely accurate, the opt-in varies by state and provider, auto
enrollment is not typical and does not happen if you buy your thermostat
at retail. But it is true getting out of the program can be a pain.