Custom function returns JSON with quotes => considered as string not as JSON

Hello,

I wrote a custom function to generate a JSON of an array. I didn't succeed to make it without code.

Although, my function is returning the good JSON, it is considered as a string with quotes and not as a JSON object. So, my API request failed.

What is a expected :

My custom function :

The return value is what is expecting:

But in fact, here what is received by the API, we can see there are quotes, so the value is considered as a whole string and not a JSON object :

What can I do in my custom code to return an JSON object and not a string ?

Thanks in advance for your help 😄