What common mistake do developers make with Status codes, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Status codes, why does the mistake cause problems, and what is the safer approach? One recurring problem with status codes is applying it without understanding the boundary it protects. Always returning status 200 for errors instead of using HTTP status codes that describe the result of the request. In addition, Response helpers can set an HTTP status code appropriate for success, validation failure, not-found conditions or server errors. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.