Someone downloads a page from your website and stores it locally. Then the user opens it and the user will be tracked and the URL might look like
This way we actually track personal data potentially by accident without knowing.
We would always exclude this protocol when tracking but allow users to opt out of this feature and do track these requests.
As this could be seen as a BC break we need to maybe wait for Matomo 5 for this and/or clearly announce this and warn users of this change.
see https://developer.matomo.org/guides/jstracker-core this would need to be changed in