Laravel Api returns Html instead of json – CPanel

Hello there my website is on cpanel and when i make an api call it returns contnet-type html instead of json note that it worked perfectly on my localhost but for some reason it isn’t working
Code

public function fetch_companies()
{
    //getting company that is linked to coupon
    $companies_id = Coupons::where('company_id' , '!=', 'null')->pluck('company_id');
    $companies = Companies::whereIn('id' , $companies_id)->get();

    return response()->json($companies);
}

i tried setting the headers to json like this

    return response()->json($companies)->withHeaders([
            'Content-Type' => 'application/json',
        ]);

but it didn’t work

here is the link to my website you may test it using postman
http://coupon-app.epizy.com/company/api/fetch

just to put you in the picture the code currently running this page is this

public function fetch_companies()

    {
        //getting company that is linked to coupon
        $companies_id = Coupons::where('company_id' , '!=', 'null')->pluck('company_id');
        $companies = Companies::whereIn('id' , $companies_id)->get();

        return response()->json($companies)->withHeaders([
                'Content-Type' => 'application/json',
            ]);
    }

if you need any information please comment and Thanks in Advance