pm2 deploy doesn't support localhost and number type port

What's going wrong?

I should deploy my app thru ssh tunneling, so that it should be deployed to localhost.
However, localhost causes deploy failure.
127.0.0.1 works well instead of localhost.

And pm2 document does not mention port for deploy target config.
port property of deploy config works, but it should be a string, not a number.

How could we reproduce this issue?

  deploy: {
    staging: {
      user: 'deployer',
      host: 'localhost',
      port: 3030,
      ref: 'origin/staging',
      repo: 'git@github.com:xxxxxx/yyyyyy',
      path: '/home/deployer/yyyyyy',
      'pre-deploy-local': '',
      'post-deploy': '. ~/.profile && yarn install && pm2 reload scripts/pm2/ecosystem.config.js --env staging',
      'pre-setup': '',
    },
  }

Supporting information

$ pm2 report

--- Daemon -------------------------------------------------
pm2d version         : 5.2.0
node version         : 16.14.0
node path            : /Users/xxxxx/.nvm/versions/node/v16.14.0/bin/pm2
argv                 : /Users/xxxxx/.nvm/versions/node/v16.14.0/bin/node,/Users/xxxxx/.nvm/versions/node/v16.14.0/node_modules/pm2/lib/Daemon.js
argv0                : node
user                 : xxxxx
uid                  : 501
gid                  : 20
uptime               : 8min
===============================================================================
--- CLI ----------------------------------------------------
local pm2            : 5.2.0
node version         : 16.14.0
node path            : /Users/xxxxx/.nvm/versions/node/v16.14.0/bin/pm2
argv                 : /Users/xxxxx/.nvm/versions/node/v16.14.0/bin/node,/Users/xxxxx/.nvm/versions/node/v16.14.0/bin/pm2,report
argv0                : node
user                 : xxxxx
uid                  : 501
gid                  : 20
===============================================================================
--- System info --------------------------------------------
arch                 : arm64
platform             : darwin
type                 : Darwin
cpus                 : Apple M1 Pro
cpus nb              : 10
freemem              : 74645504
totalmem             : 17179869184
home                 : /Users/xxxxx
===============================================================================

Start by tracing the pm2 deploy entry point that handles the shown staging configuration, then reproduce the failure with host set to localhost and port set to 3030. Done means localhost deploys through the SSH tunnel, numeric ports work, and the deploy configuration documentation describes the port property.