RateLimited middleware not working in Laravel 9 Job - php

Question

I'm trying to send email notifications to my app users, limiting the number of emails to only 2 per minute, so as not to breach my email provider's allowed sending rate. So in MailingController.php I have:
<?php
namespace App\Http\Controllers;
use App\Jobs\SendMessages;
use Illuminate\Http\Request;
class MailingController extends Controller
{
public function send(Request $request) {
SendMessages::dispatch();
return redirect()->back()->withSuccess('Successful operation.');
}
}
SendMessages.php content is:
<?php
namespace App\Jobs;
use Illuminate\Bus\Queueable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Queue\InteractsWithQueue;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Foundation\Bus\Dispatchable;
use App\Jobs\Middleware\RateLimited;
use Illuminate\Auth\Notifications\VerifyEmail;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Mail;
use Illuminate\Support\Facades\RateLimiter;
use Illuminate\Support\Facades\Redis;
class SendMessages implements ShouldQueue
{
use Dispatchable, InteractsWithQueue, Queueable, SerializesModels;
public $timeout = 7200;
/**
* Create a new job instance.
*
* #return void
*/
public function __construct()
{
}
/**
* Execute the job.
*
* #return void
*/
public function handle()
{
$users = User::all();
foreach ($users as $user) {
Log::debug('SendMessages#handle() ' . $user->email);
$user->notify(new VerifyEmail);
}
}
public function middleware()
{
return [new RateLimited];
}
}
And finally, RateLimited.php content is:
<?php
namespace App\Jobs\Middleware;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Redis;
class RateLimited
{
/**
* Process the queued job.
*
* #param mixed $job
* #param callable $next
* #return mixed
*/
public function handle($job, $next)
{
Redis::throttle('key')
->block(0)->allow(1)->every(30)
->then(function () use ($job, $next) {
// Lock obtained...
Log::debug('RateLimited');
$next($job);
}, function () use ($job) {
// Could not obtain lock...
$job->release(16);
});
}
}
All these are copied and pasted from a Laravel 8 application that works perfectly fine, sending one email every 30 seconds as expected, but in my brand new Laravel 9 application the same code no longer works, and all email notifications are sent at once. I know I must be missing something, but have ran out of ideas. Any help would be greatly appreciated.
Thank you.