Good question, I had to check myself to be sure. Running state. From the docs about this automation: "This event fires if a flow is late to start, i.e. the flow has not entered a running state some time after the scheduled start time"
So it checks the time your flow run needed to transition from the Scheduled state into a Running state. Submitted state is a Meta state of Scheduled (a wrapper around a Scheduled state) that adds additional metadata to the Scheduled state