Why laravel doesn't validate 'form-data' request?

//TestRequest.php
public function rules()
{
    return [
        'name' => 'string|required|min:5',
        'tip' => 'string|required|min:5',
        'answer' => 'string|required',
        'image' => 'file|required|mimes:png,jpg,jpeg'
    ];
}


//TestController.php
public function put(TestRequest $request)
{
    $validated = $request->validated();
}

I'm doing some rest API. I need a form with some text fields and one image upload field but I have a problem with validating it.

1. When I'm sending the request as 'form-data' in the Postman, Laravel doesn't see in the validation any fields (why?).

Response none of fields validated even if it's send to Laravel

{
    "message": "The given data was invalid.",
    "errors": {
        "name": [
            "The name field is required."
        ],
        "tip": [
            "The tip field is required."
        ],
        "answer": [
            "The answer field is required."
        ],
        "image": [
            "The image field is required."
        ]
    }
}

1. When I'm sending the request as application/x-www-form-urlencoded Laravel sees my text fields, but I can't, of course, upload the image. (I don't see how to upload image that way in Postman. I think it's not possible)

Response - name, tip and answer field validated correctly, but I can't add "image"

{
    "message": "The given data was invalid.",
    "errors": {
        "image": [
            "The image field is required."
        ]
    }
}

API will be used by the android APP. How I can solve this? How I can have both validation on text and file inputs?