Another way to do this.
Create another field, this field does not have to be an ACF field. It will be a true/false field of sorts holding either a 1 or a 0. This flag will indicate if the event dates have passed.
Create a CRON (https://developer.wordpress.org/plugins/cron/), there may be plugins that let you do this. That queries events where the date has passed and sets this flag to 1.
Order posts by this field first, then the start and end date.
