I'm pretty sure that this scene is from Unrivaled Tang Sect or from Legend of The Dragon King. But I don't know which one. I vaguely remember a scene where a tree spirit had raised a rare plant spirit for many years and gained its trust only to consume it when it reached a certain age.
do you have a chapter or arc in mind? maybe it was saved? I just remember the tree wanting to eat it. I can't say for sure that it ate it for sure