Tado changed their system to a subscription service that offers extra features. They are called “skills”.
For instance in the old version (the one I have) having your heating turned on/off based on whether you are home is a free feature. In the current/new version if you buy a Tado system you have to pay a subscription to use this service.
I presume that that flag is used to determine if you are on the old or the new system.