When you turn your auto reply on, to run in the future, it’s in a “waiting mode”
– the button right to the auto reply changes its color
– outline arrow icon appears in the notification bar
When you turn auto reply on, to run right now, or it turns into the “active / running mode”
– background of the auto reply changes to light blue
– filled arrow icon appears in the notification bar
the phone is silent (if not set different)