(it's) no/little/small wonder (that)... spoken language
Said when you find something not surprising at all.
This is one of the most complex mazes in the world, so it is little wonder that they got lost.
This a well-paid job so, it's small wonder that many people applied for it.
A: What! John solved that puzzle in just a few seconds? B: Yup! No wonder he is able to pull it off so quickly. He is one of the best brains in the country.
This phrase was formed based on the meaning of the noun "wonder".