Originally Posted by
catocony
US citizens don't need a passport to enter the US, so there is no formal tracking of you in that "he entered on a US passport but is departing on an EU one".
assuming you are replying to my post, the concern really is: Jacques is departing the US with his French passport in the airline record, but there is no record that Jacques ever entered the US (because Jacques used his US passport to comply with US law).
Whether that is going to be a problem I don’t know. At this time I am departing the US with my US passport in my airline record, so I have no personal experience.