panel-pelican-dev/app/Http/Middleware/MaintenanceMiddleware.php

<?php

namespace App\Http\Middleware;

use App\Models\Server;
use Closure;
use Illuminate\Contracts\Routing\ResponseFactory;
use Illuminate\Http\Request;

class MaintenanceMiddleware
{
    /**
     * MaintenanceMiddleware constructor.
     */
    public function __construct(private ResponseFactory $response) {}

    /**
     * Handle an incoming request.
     */
    public function handle(Request $request, Closure $next): mixed
    {
        /** @var Server $server */
        $server = $request->attributes->get('server');
        $node = $server->getRelation('node');

        if ($node->maintenance_mode) {
            return $this->response->view('errors.maintenance');
        }

        return $next($request);
    }
}