Can only track ~60% from Facebook


we have been testing out Matomo for a little while now.
While we have no problem tracking users from Google Ads & other campaign sources, we seem to only be able to track ~60% of the users coming from Facebook. We have checked around quite a bit (it seems to be not Device/Browser/Extensions/…) but seem to be not be able to reproduce it ourselves. This is the case across multiple domains.

Example: While we have 1000 Link-Clicks coming from Facebook to our Website, we can only track ~600. We use UTM Parameters and Matomo’s Campaign Reporting Plugin.

Is someone having similiar experiences or has ideas what this could be? While some people will perhaps jump off, 40% seem very high and our page loading speed is good.

Thank you already for any input.

Remember that Matomo truly honors the “do not track” flag who comes opted in in latest browsers now.
Also it could depends on browser’s privacy extensions blocking your tracking.
If you trust the 1000 clicks are true on other platform, then stay stick to the other platform.
Analytics isn’t an absolute fact about concurrent softwares but a relative fact between periods.