Your nginx log shows the following error:
2020/05/11 16:22:53 [error] 3077#0: *12506 FastCGI sent in stderr: "PHP message: PHP Parse error: syntax error, unexpected end of file in /opt/bitnami/apps/wordpress/htdocs/wp-content/plugins/monit.php on line 87" while reading response header from upstream, client: xxx.xxx.xxx.xx.xx, server: localhost, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://unix:/opt/bitnami/php/var/run/www.sock:", host: "xx.xx.xx.xx", referrer: "http://xxx.xxx.xx/"
It seems the monit plugin does not have a well written PHP file. Could you check if disabling it solves the issue? To disable it you can access through SSH and then run the following command:
wp plugin deactivate monit