Node Endpoint 403 Fix

My Node-based API has an endpoint that suddenly refuses requests whenever certain query or path parameters are present. The headers and body reach the server just fine, but as soon as those parameters hit the route, the call dies with a 403 Forbidden... (Budget: £20 - £250 GBP, Jobs: API Development, Debugging, JavaScript, MySQL, Node.js, PHP, RESTful API, Software Development, Software Engineering, Web Development)