How to re-write exposed form multi-select query key identifiers?

I'm wondering if there's a way to update the "identifiers" (not sure of the terminology) of a key from the URL when setting an exposed form field to multi-select?

The key pattern in the URL is key%5B0%5D=238.

Looking in the Request Stack $this->requestStack->getCurrentRequest(), these options are returned as an array:

key
  0 => 13
  1 => 238

I'm currently working in a custom class class CustomBlock extends BlockBase implements ContainerFactoryPluginInterface.

The intent is to create links for each filter option that remove an individual selection from the URL.

Edit: Below is the updated code I am working with. This all seems to work with testing, but I did expect the identifiers to update so am not 100%:

public function build() {

  $q_parameters = $this->requestStack->getCurrentRequest()->query->all();
  $pills = "";

  foreach ($q_parameters as $key => $value) {

    if ($key !== $someValue) {

      if (is_array($value)) {
        foreach ($value as $k => $v) {

          $newValue = $value;
          unset($newValue[$k]);
          $pillOptions = [
            'query' => [
              $key => $newValue, // This doesn't re-sequence the identifiers.
            ],
            'attributes' => [
              'class' => [
                'class',
              ],
            ],
          ];
          $pillUrl = Url::fromUserInput($this->requestStack->getCurrentRequest()->getRequestUri(), $pillOptions);
          $pills .= Link::fromTextAndUrl($name, $pillUrl)->toString();
        }
      }
      else {
        $pillOptions = [
          'query' => [
            $key => "All",
          ],
          'attributes' => [
            'class' => [
              'class',
            ],
          ],
        ];
        $pillUrl = Url::fromUserInput($this->requestStack->getCurrentRequest()->getRequestUri(), $pillOptions);
        $pills .= Link::fromTextAndUrl($name, $pillUrl)->toString();
      }
    }
  }

  return [
    '#markup' => $pills,
  ];
}

If the array looks like:

key
  0 => 13
  1 => 238

The path query looks like:

key%5B0%5D=13&key%5B1%5D=238

The links generated do remove the unset array key, though the unique identifiers do not update, e.g. I would have thought they'd be reset to sequential %5B0, %5B1, etc.

The part in question is setting the array to the query attribute as:

$pillOptions = [
  'query' => [
    $key => $newValue,
  ],
];

Is it possible to re-sequence the key identifiers? Or is it even necessary?