[Bug] Matomo track page view on preload/prerender

What happened?

When a developer configures the preload/prerender function on his website in order to optimize the loading time of his pages, Matomo is triggered and counts the page (even though the page has not yet been displayed on the user's screen).

What should happen?

Matomo should handle preloading and not save the page view when the page has a preload or prerender request header. Tested with GA4 (it differentiates between classic page view and pre-rendered page view and does not follow pre-rendered page view).

How can this be reproduced?

Create a website with 3 pages
Add Matomo on every page (as usual).
On page 1 add a script to preload page 2 and 3
Visit page 1 with your browser
Discover that Matomo fired on every preloaded pages, (user only visited page 1).
Move to page 2, Matomo will be triggered again (normal situation).

Then you have :

1x page 1
2x page 2
1x page 3

Instead of :
1x page 1
1x page 2

Matomo should detect the header in preload request and disable data recoding in their database.

If you look for the preload script, here is a basic example you can copy and paste on your page :
```
<script type="speculationrules">
  {
    "prerender": [
      {
        "where": {
          "href_matches": "/*"
        },
        "eagerness": "immediate"
      }
    ]
  }
</script>
```

PS: To be sure that preload is active on your browser, you can view preloaded URLs within Chrome Dev Tools (Application > Speculative loads)

Thank you Ronan HELLO

Matomo version

5.1.2

PHP version

8.3

Server operating system

Debian

What browsers are you seeing the problem on?

Chrome

Computer operating system

Windows and Mac

Relevant log output

No response

Validations

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[X] Follow our Security Policy.
[X] Check that there isn't already an issue that reports the same bug to avoid creating duplicates.
[X] The provided steps to reproduce is a minimal reproducible of the Bug.

matomo-org / matomo