Guzzle client. Working with params on remote API that has a param Array of strings json

I am working with an API (Cpanel) that in some endpoints allows the passing of a parameter made up of an array of string json

As it has many endpoints I had already structured everything as a base class in which I mount the call -> get through a Guzzle client.

$response = $client->get($endpoint, [
    'headers' => [
        'Accept' => 'application/json',
        'Authorization' => 'whm root:' .config('whmapi.token')
    ],
    'query' => $this->params
]);

The problem is that none of the options I have tried has been correct, except for a somewhat far-fetched one.

array of json

add={"dname":"em5768.pruebas.com","ttl":3600,"record_type":"CNAME","data":["u23123539.wl040.sendgrid.net"]}&add={"dname":"em5769.pruebas.com","ttl":3600,"record_type":"CNAME","data":["u23123540.wl040.sendgrid.net"]}

Way 1

Create a method on class for this action, that get array of array and convert in a unique param

$params = [
"api.version" => 1
  "serial" => 2021121005
  "zone" => "pruebas.com"
  "add" => "{"dname":"em5768.pruebas.com","ttl":3600,"record_type":"CNAME","data":["u23123539.wl040.sendgrid.net"]}&add={"dname":"em5769.pruebas.com","ttl":3600,"record_type":"CNAME","data":["u23123540.wl040.sendgrid.net"]}"
]

This fails because Guzzle decode & in the middle of the param add

Working way that works

public function getRequest(bool $params = true)
{
    $client = new Client();

    $endpoint = $this->endpoint;

    // @todo I needs improve
    if (!empty($this->stringify_params)) {
        $stringify = '?';
        foreach ($this->stringify_params as $key => $param) {
            $stringify .= $key . '=' . $param . '&';
        }
        $stringify = rtrim($stringify, '&');
        $endpoint .= $stringify;
        $this->params = [];

	    // I needs this because if `query` is equals to empty array remote API fails
        if ($params) {
            $response = $client->get($endpoint, [
                'headers' => [
                    'Accept' => 'application/json',
                    'Authorization' => 'whm root:' .config('whmapi.token')
                ],
            ]);
        }
    } else {
        if ($params) {
            $response = $client->get($endpoint, [
                'headers' => [
                    'Accept' => 'application/json',
                    'Authorization' => 'whm root:' .config('whmapi.token')
                ],
                'query' => $this->params
            ]);
        }
    }

    return $result;
}