"Getting to this point isn’t unusual. Clients clearly think they’re making the call correctly, or else they would fix the endpoint themselves. Some misspellings are difficult to catch. The enum USER_RETREIVE may not be noticed from USER_RETRIEVE, especially if picking it from a list. Misspellings happen and they’re not always caught before making it to the contract. As an aside, that’s why it’s important writers routinely check development’s changes. This applies, too, to our testing calls in Postman, where manually entering endpoints and values are more pervasive.
The reason this isn’t caught is simple: We’re not expecting it.
For our testing, the call is made and we get results. We may even spot check some of them. But generally, results aren’t examined that closely. For instance, how often do you so carefully examine a returned list of 50 or 100 items? You check may check that the objects are complete but not that the list conforms to the search criteria.
The reason this happens is because of an intentional behavior on the server. This behavior is called Lenient Handling or Strict Handling."
https://robertdelwood.medium.com/understanding-query-parameter-handling-in-rest-calls-1821e0c3fa8c