PHP Fatal error: Uncaught Error: mysql_get_server_info()

I am getting this error:
PHP Fatal error: Uncaught Error: Call to undefined function mysql_get_server_info() in /home/zzbtaeeo/public_html/check_charset.php:46

I can’t edit with Elementor. I did all normal processes like memory limit, PHP version upgrade, and also did uninstall in reinstall all plugins besides Elementor.
But I can’t get rid of this problem.
Please help me to get rid of this problem.