Almost none of the YouTube/blogs recommending this mention it or seem to be aware (or have just clicked through and granted the permission without thinking about it), but it absolutely does require screen recording to operate.
The DisplayLink driver requires your admin password to install, and installs itself as a background process that records the screen constantly in order to software render the extra display. There are other similar products, they all work this way.
From DisplayLink’s own website:
https://support.displaylink.com/knowledgebase/articles/19509...
