Hi,
I don't read Dutch, so I'm not sure what it is saying. However, based on what I know, it seems that the "verwijzende pagina" is the referrer URL.
If I access these pages on your website, I don't see the faulty URL present on the page.
What that means is that these are old URLs that were present there in the past but are not there anymore.
However, I think there is a way to improve things.
I can see on the page
everybody-lingerie.nl/index.php?option=c...&category_pathway=56
that you have a canonical URL set:
i.imgur.com/eEeBkW8.png
However, it is set with just the current URL used to access the page.
This should normally be set with the main URL you want to be used to access the product page.
I think the problem is that you've activated the system - SEF plugin via the Joomla plugins manager. But you should not do that.
This plugin adds wrong canonical tags to the pages:
github.com/joomla/joomla-cms/discussions/31806
So disable it. I think that's why Google indexes wrong URLs on your website.
Then, I would recommend you set the "canonical URL" setting in your products with the main URL you want to be indexed. That way, it will clean the search results on your website when Google reindexes your URLs.