Headless Pages Still Rendering

I am using a custom theme. I am reading docs on headless and .DisableKinds, but I am still having issues.

I have a section structure like this

my_section/_headless_content/
my_section/content_a/
my_section/content_b/
...
my_section/content_n/

where _headless_content looks like this

my_section/_headless_content/a.md
my_section/_headless_content/b.md
...
my_section/_headless_content/n.md

I am using custom layouts to create my section pages as desired (.GetPage…). However, I notice that these headless pages are still being rendered.

www.mysite.com/my_section/_headless_content/x is still being created despite setting headless: true in the front matter.

Is there an error? How do I prevent these pages from being rendered? Thanks!

Updating the front matter works as shown below.

headless: true
_build:
  list: "never"
  publishResources: true
  render: "never"

I am not sure why headless: true doesn’t work, or when I might want headless: true but not render: "never"

Reference:

_build
 render: never

The page will not be included in any page collection.
headless: true

A headless bundle is a bundle that is configured to not get published anywhere:

    It will have no Permalink and no rendered HTML in public/.
    It will not be part of .Site.RegularPages, etc.