How to auto populate a field upon status change in RTC

Accepted answer

You can detect the state, but it is very hard to detect the state change in a calculated value. This is achievable using customization, but, as far as I am concerned, not feasible to do it with attribute customization. It would require a follow up action to do it properly.
Comments

There is a really terrible way to use attribute customization with JavaScript to somehow detect a state change, I think has been used by some users. It requires to use an attribute to store the state. Compare theat value with the state attribute to be able to see the state has changed and then act. I do not like this solution at all and have not implemented it. I have heared about users that apparently did......