What happened?

Description

The new feature in #15397 doesn't appear to be working correctly. I tried applying a as headersFilter in the app.web.php but this applied to Control Panel requests not site Requests.

Example config used in app.web.php:

// Attach the headers filter to the application
'as headersFilter' => [
    'class' => \craft\filters\Headers::class,
    'site' => 1,
    'headers' => [
        'X-Test-Header' => 'Test Value',
    ]
]

For a site request:

For a CP request:

Steps to reproduce

1. Add as headersFilter example in Configurable CORS and site headers #15397
2. Inspect response headers of a site request (value is not present)
3. Inspect response of CP request e.g. /admin (value is present)

Expected behavior

Headers to be present on site requests only.

Actual behavior

Site requests do not have any headers added, but are appearing on Control Panel requests which is the reverse of intended functionality.

Craft CMS version

5.3.0.3

PHP version

8.3

Operating system and version

No response

Database type and version

MySQL

Image driver and version

No response

Installed plugins and versions

No response