the moon is crumbling, but that's okay

I know this kind of falls under unreliable narrator but is there a name for the literary device where the narrator suddenly reveals a crucial piece of information to the reader out of nowhere like it's nbd. like in villette when she doesn't tell us who the doctor is or that she recognized him until a hundred pages later. or also in villette when after four hundred pages of paul locking her in attics and yelling at her for looking at paintings she's suddenly like "oh I might not have mentioned that every day he also left little presents in my desk. just books and bonbons and stuff like that, that he thought I might like. I might have forgotten to mention that part. anyway" and just goes on with the story. maybe we should call it the lucy snowe gambit

Jing Zhiyong (Chinese b. 1982), Insomnia, 2026, Oil on canvas