validating an array of files sent by ajax

hello, I've got this ajax request, I tried several ways to validate photo array, but every time I got an internal server error

let data = new FormData();
data.append('text', $('#text').val());
data.append('photos', uploaded_files);
// uploaded_files is an array of images
​
$.ajax({
    headers: {
        'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
    },
    url: '/profile/newPost',
    method: 'POST',
    data: data,
    contentType: false,
    processData: false,
    success: function(response){
        console.log("response: ",response); 
    },
    error: function(jqXHR, textStatus, errorThrown) {
        console.log("error: " + textStatus + ' : ' + errorThrown);
}

this is my controller, but it doesn't work for me, don't know why

$data = $request->all();
​
$validator = Validator::make(
  $data, [
  'photos.*' => 'required|mimes:jpg,jpeg,png,bmp|max:20000'
  ],[
    'photos.*.required' => 'Please upload an image',
    'photos.*.mimes' => 'Only jpeg,png and bmp images are allowed',
    'photos.*.max' => 'Sorry! Maximum allowed size for an image is 20MB',
  ]
);
​
if ($validator->fails()) {
  // Validation error.. 
}

could anyone help me please