ot_typo3/ot_core/Configuration/RequestMiddlewares.php

<?php
use Opentalent\OtCore\Middleware\Frontend\OtSiteResolver;

/**
 * Register middlewares, which will be triggered at each request
 */
return [
    'frontend' => [
        'typo3/cms-frontend/site' => [
            'target' => OtSiteResolver::class,
            'before' => [
                'typo3/cms-frontend/page-resolver'
            ]
        ],
    ],
];