PHP 8 Error

Hello guys
after i follow the guide i get this error. when i hit Get status or remove. How i can fix it ?
2021/07/01 06:59:42 [error] 21056#21056: *282 FastCGI sent in stderr: “PHP message: PHP Fatal error: Uncaught TypeError: implode(): Argument #2 ($array) must be of type ?array, string given in /root/wp-content/plugins/fast-indexing-api/vendor/google/apiclient/src/Google/Service/Resource.php:297
Stack trace:
#/root/wp-content/plugins/fast-indexing-api/vendor/google/apiclient/src/Google/Service/Resource.php(297): implode()
#1 /root/wp-content/plugins/fast-indexing-api/vendor/google/apiclient/src/Google/Service/Resource.php(190): Google_Service_Resource->createRequestUri()
#2 /root/wp-content/plugins/fast-indexing-api/vendor/google/apiclient-services/src/Google/Service/Indexing/Resource/UrlNotifications.php(43): Google_Service_Resource->call()
#3 /root/wp-content/plugins/fast-indexing-api/includes/class-instant-indexing.php(241): Google_Service_Indexing_Resource_UrlNotifications->getMetadata()
#4/root/wp-content/plugins/fast-indexing-api/includes/class-instant-indexing.php(212): RM_GIAPI->send_to_api(” while reading response header from upstream, client: 162.158.111.103, server: etswak.net, request: “POST /wp-admin/admin-ajax.php HTTP/1.1”, upstream: “fastcgi://unix:/run/php/php8.0-fpm.sock:”, host: “etswak.net”, referrer: “https://etswak.net/”