Question: Processor load 100% when I run an application under load

Hello everyone,
I ran into the following problem, there is an application written in Nuxt 2 and used to run the process manager pm2, on startup at the slightest load (+ - 10 requests per second), the server crashes at 100% CPU load.
The application is running in cluster mode, the server itself is 8vCPU, 16 GB.
Maybe there are some tools for profiling, and figuring out what's going on inside. The application is running on a DigitalOcean droplet, without containers or anything else. Reverse proxy via Nginx

Ecosystem.config.js

module.exports = {
  apps: [
    {
      name: 'wingly',
      script: './node_modules/nuxt/bin/nuxt.js',
      args: 'start',
      port: 3000,
      instances: 'max',
      exec_mode: 'cluster',
      cwd: './',
    },
  ],
}

Start with ecosystem.config.js and reproduce the reported load using the Nuxt 2 application in PM2 cluster mode behind Nginx. Profile the Node.js processes under roughly 10 requests per second; done requires identifying whether PM2, clustering, Nuxt, or the application causes the 100% CPU load and documenting a confirmed fix.