As the world reacts to players actions, certain NPCs might be in the dark of said action. If it’s plausible that they might not have learned this fact you could omit this NPCs reaction.
Roll for uncertainty
If it’s possible for the NPC to either know or not know, you could roll a D20, choosing your own DC!
Reference
E. Schea, M. (2018). Sly flourish’s return of the lazy dungeon master. Sly flourish shop
Highlights or timestamps
Return of the Lazy Dungeon Master Highlights
- Given the last actions of the characters, what are the villains doing in response? Maybe one or more of the villains don’t know what the characters did.
— ^ed3011 from Return of the Lazy Dungeon Master highlights