Laravel request remove fields before validation

I am trying to remove some fields before they are validated.
Trying to attempt this inside prepareForValidation()

use Illuminate\Foundation\Http\FormRequest;

class VideoRequest extends ApiRequest
{

    // ..code..

    protected function prepareForValidation()
    {
        $this->merge([
            'public' => $this->toBoolean($this->public),
            'notify' => $this->toBoolean($this->notify),
        ]);

        $video_id = $this->route('video_id');
        if($this->isMethod('put') && Video::salesStarted($video_id)){
            Log::info('removing sales');
            // attempt 1
            $this->except(['sales_start', 'tickets', 'price']);
            // attempt 2
            $this->request->remove('sales_start');
            // attempt 3
            $this->offsetUnset('sales_start');
        }
        if($this->isMethod('put') && Video::streamStarted($video_id)){
            Log::info('removing streams');
            // attempt 1
            $this->except(['stream_start', 'stream_count', 'archive']);
            // attempt 2
            $this->request->remove('sales_start');
            // attempt 3
            $this->offsetUnset('sales_start');
        }
        
        $thumb = $this->uploadThumbnail($video_id);
        if($thumb !== null){
            $this->merge($thumb);
        }
    }

    // ..code..

}

I made sure the code was entering inside the if statement, however the fields are not being removed.

Running $this->request->remove() and $this->except() have no effect.
If I add safe() it throws Call to a member function safe() on null.
I also tried to use unset() but nothing seems to work.

The rules for the dates are like so:

'sales_start' => 'sometimes|required|date|after:now|before:stream_start',
'stream_start' => 'sometimes|required|date|after:now',

but the $request->validated() returns the errors although it shouldn't be validating the deleted fields.

"sales_start": [
    "The sales start must be a date after now."
],
"stream_start": [
    "The stream start must be a date after now."
]

Why are the fields not being deleted?

Edit

As requested I added some code.
This is what ApiRequest looks like:

use Illuminate\Http\Exceptions\HttpResponseException;
use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Contracts\Validation\Validator;

abstract class ApiRequest extends FormRequest
{
    protected function failedValidation(Validator $validator): void
    {
        $response['data']    = [];
        $response['api_status']  = 'ng';
        $response['status_message'] = 'failed validation';
        $response['errors']  = $validator->errors()->toArray();

        throw new HttpResponseException(
            response()->json( $response, 422 )
        );
    }

    protected function toBoolean($booleable)
    {
        return filter_var($booleable, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);
    }
}

And the request is called from the controller like so:

public function update(VideoRequest $request, $video_id)
{
    ... some code ...

    $validated = $request->validated();

    ... some code ...
}

so $this refers to the VideoRequest that extends FormRequest.

Solution

None of the above is really correct, but the following will work.

In protected function prepareForValidation(), you can do something like this:

protected function prepareForValidation()
{
   $input = $this->input();

   unset($input['my_key']);

   $this->replace($input);
}

That will let you change and replace data before it's validated.

Of course you can also collect() the $this->input() data before working with it, if you prefer to work with a collection.