I have no idea, but you say it's a GET request, but the screenshot shows a POST request.
If it's supposed to be a GET request, then the array needs to be encoded specific to the backend as there is no standardised way of passing an array in a query string (and it has to be query string because GET requests don't have a body).
https://stackoverflow.com/questions/6243051/how-to-pass-an-array-within-a-query-string
What is the cURL command you have used that works? It might make it clear what isn't working