Please check the access log..then see the user agent or bot whose status is burdening your server,..then please make conditions in your nginx configuration..
like the example I made ...
https://www.aapanel.com/forum/d/3947-this-is-what-causes-the-server-to-down
Waf Nginx does not provide a good solution for me ... because when I activate the waf nginx plugin, my website has a problem, which is it cannot be accessed or sometimes visitors are blocked and my Android api application is also sometimes blocked by waf nginx ...😂🙏
Therefore, I use the method above ...