PM2 cluster mode additional processes use wrong script path

I have a nodejs app running on a server with the following ecosystem.config.js:

    module.exports = {
      apps : [
    {
        name      : "app.website.com",
        script    : "/var/www/app.website.com/node/server.js",
        cwd       : "/var/www/app.website.com/node/",
        instances : "max",
        exec_mode : "cluster",
        max_memory_restart: "500M",
        out_file  : "/var/log/pm2.app.website.com.out.log",
        error_file: "/var/log/pm2.app.website.com.err.log",
        merge_logs: true,
        pid_file  : "/var/run/pm2.app.website.com.pid"
    },
    {
        name      : "dev1.website.com",
        script    : "/var/www/dev1.website.com/node/server.js",
        cwd       : "/var/www/dev1.website.com/node/",
        instances : 1,
        exec_mode : "cluster",
        max_memory_restart: "500M",
        out_file  : "/var/log/pm2.dev1.website.com.out.log",
        error_file: "/var/log/pm2.dev1.website.com.err.log",
        merge_logs: true,
        pid_file  : "/var/run/pm2.dev1.website.com.pid"
    },
      ]
    }

When I start this, I see in pm2 status:

• 3 processes started for app.website.com
• 2 of them constantly restarting

in pm2 monit

I see that one of the 3 processes has a script path of

/var/www/app.website.com/node/server.js

whereas the 2 others have a script path of

/var/www/app.website.com/node

therefore they are erroring.

I can't see why the script paths of the 3 processes would not be the same?

Pm2 version 5.1.1 nodejs version 14.17.6