The Hunger Games: The Ballad of Songbirds and Snakes movie killed off Clemensia, despite her having survived in the book, but this was the best way to fix a larger problem. In both versions of the Hunger Games prequel story, the mentor was attacked by Dr. Gaul's rainbow snakes after she claimed to have written a homework assignment rather than Snow. This scene was a way of demonstrating how dangerous Gaul was to District and Capitol children alike, a fact that is was far easier to drive home in the Ballad of Songbirds and Snakes book than in the movie. Still, Clamensia was one of the few who survived the cruel woman's wrath, something the film negated.

https://screenrant.com/ballad-songbirds-snakes-clemensia-mentor-deaths-fix/