mongoose post update hook triggered even no document is updated

Question

when I use mongoose updateOne to update a document with its id and additional query for optimistic locking as below

Model.updateOne({_id,...additionalQueryForOptimisticLock},updates)

if there is a conflict write, it returns as expectation;:

{
  acknowledged: true,
  modifiedCount: 0,
  upsertedId: null,
  upsertedCount: 0,
  matchedCount: 0
} 

but I don't expect that it still trigger the post update hook, is it a bug? thanks!