Each token has a base value which belongs to the default system state. And unless overridden, this base value is inherited in all other states.
If a token is overridden in the active state, then it is marked with this colored circle, both on the tokens panel and token item editor:
State Indicators are also shown on the header of token item editors, and clicking these buttons will show the list of actions to manage overriden value:
➥ If the token is customized in the active state, then the marker is blue circle and you can remove the overridden value from the menu.
➥ Moving the overridden value to another state.
➥ Moving the overridden value to default state.
➥
If the token value is not overridden in active state but is inherited from a parent state, then the marker color becomes orange and the popup shows the state the value inherited from.