First of all, I replaced your API Key with THE_KEY.
So this conversation can remain public without the risk of someone stealing your API Key.

The movie you're looking for is this:
https://www.themoviedb.org/movie/592834-my-spy

The API Request you posted, get / movie / {movie_id},

https://api.themoviedb.org/3/movie/592834?api_key=[THE_KEY]&language=tr-TR&append_to_response=credits&certification_country=US&certification.lte=R

looks like it is using filter features from the API Request get / discover / movie.
The last two parameters you used,
&certification_country=US and &certification.lte=R,
are used only in discover requests, not get/movie requests.

I made your request and received only the data for a normal get / movie / {movie_id}.
https://api.themoviedb.org/3/movie/592834?api_key=[THE_KEY]&language=tr-TR&append_to_response=credits&certification_country=US&certification.lte=R
The two extra parameters were disregarded.
I don't know why you got that answer:

response: {"status_code":34,"status_message":"The resource you requested could not be found."}

I think it is worth checking if this was the API Request sent.
I received an answer without problems.

As for the fact that POSTMA is able to obtain results with exactly the same Requisition, I cannot explain the reason.
Only the creators of POSTM can inform.
Perhaps the answer that Postman received was the same as I received.

EDIT
This response code

 {"status_code":34,"status_message":"The resource you requested could not be found."}  

always appears when there is an error in the TMDb ID, and the ID sent refers to an entry for a movie that has been deleted.
The error may be in the ID.

I found the answer: worked when ajax post type was removed.

this working state:

        $.ajax({
            url: "https://api.themoviedb.org/3/movie/" + id + "?api_key=api_key&language=tr-TR&append_to_response=credits&certification_country=US&certification.lte=R",
            contentType: "application/json",
       dataType: 'json',
            success: function (data) {
                console.log(data);

            },
            error: function (data) {

            }
        });

this not working state:

        $.ajax({
            url: "https://api.themoviedb.org/3/movie/" + id + "?api_key=api_key&language=tr-TR&append_to_response=credits&certification_country=US&certification.lte=R",
          **type:'POST'**
            contentType: "application/json",
       dataType: 'json',
            success: function (data) {
                console.log(data);

            },
            error: function (data) {

            }
        });