I have an ecobee 4 thermostat, and it’s connected to HA via the HomeKit Controller integration.
When the thermostat is set to Auto (Heat/Cool), temperature control doesn’t seem to work right. I can set heat temp = cool temp, even though the ecobee doesn’t allow it. It would set one of the two temps to the correct temp. Also, HA would show that both temp are set, making the actual temp settings different from what’s shown in HA.