While fewer characters have left the 9-1-1 franchise compared to other procedurals, Ryan Murphy’s hit shows 9-1-1 and 9-1-1: Lone Star have also experienced premature character departures. The franchise has been praised for mixing first responders together to create highly entertaining crime dramas. As with the ever-changing cases that the teams have experienced, the 9-1-1 and 9-1-1: Lone Star casts have also changed significantly since their respective premieres, as several characters have had to say goodbye to the franchise.

https://screenrant.com/911-lone-star-characters-exit-reasons/