https://www.looper.com/2031781/emily-wickersham-ellie-bishop-ncis-exit-explained/

Why did Emily Wickersham's Ellie Bishop leave "NCIS" at the end of Season 18? Here's what the actor has said about her departure from the show.

CBS Clears The Path For Ellie Bishop’s NCIS Return (https://screenrant.com/ncis-ellie-bishop-emily-wickersham-return-clear/)

4 years after Emily Wickersham's rather unexpected exit from the procedural, CBS paves the way for Ellie Bishop's return to NCIS via season 23.