I'm using the "https://aladhan.com/islamic-calendar-api" in my PHP/Laravel application
Here is my code
public static function DateToHijri($gregorianDate)
    {
        $gregorianDate = '2024-12-03'; // the input
        $dateFormat = date('d-m-Y', strtotime($gregorianDate));
        $date = Http::get('http://api.aladhan.com/v1/gToH/' . $dateFormat)->json();
        dd($gregorianDate, $date);
    }
the result 
"2024-12-03" // app\Models\Day.php:54
array:3 [▼ // app\Models\Day.php:54
  "code" => 200
  "status" => "OK"
  "data" => array:2 [▼
    "hijri" => array:8 [▼
      "date" => "01-06-1446" // NOT 01 IT 02
      "format" => "DD-MM-YYYY"
      "day" => "01" // NOT 01 IT 02
      "weekday" => array:2 [▼
        "en" => "Al Thalaata"
        "ar" => "الثلاثاء"
      ]
      "month" => array:3 [▶]
      "year" => "1446"
      "designation" => array:2 [▶]
      "holidays" => []
    ]
    "gregorian" => array:7 [▶]
  ]
]
Check the reference I used to check the date 
https://www.ummulqura.org.sa/yearcalender.aspx?y=1446&l=True