Ch-15 - spawn / process.env

Hi, when I run the following code

'use strict'
const { spawn } = require('child_process')

const sp = spawn(process.execPath, ['-p', 'process.env'], {
  env: {SUBPROCESS_SPECIFIC: 'ENV VAR'}
})

sp.stdout.pipe(process.stdout)
console.log('total var::', Object.keys(process.env).length)

I get the result

total var:: 39
{
  SUBPROCESS_SPECIFIC: 'ENV VAR',
  __CF_USER_TEXT_ENCODING: '0x1F5:0x0:0xF'
}

My question is

1. what and why is __CF_USER_TEXT_ENCODING: '0x1F5:0x0:0xF' in the outout? is this expected?
2. the total length of process.env is 39. is this correct or it should be 2?

I am assuming it still got other environment variables in the process because when I console.log(process.env) I see heaps of them.

What am I doing wrong ?

Thanks