The "Find links" function sends a request to an external backlink database / backlink checking tool called (SEOkicks.de) to see if their crawler has already found backlinks for the requested domain in the past. As you know, none of these tools are 100% accurate. We therefore recommend that you also look at other backlink checking tools, or Google Search Console. Export the results and import them into linkbird. It´s a bit of boot-strapping, but we can assure you it´s worth the effort!
When the data is passed to linkbird, it checks for duplicates. Please note: "sitewide links" are only imported once and only online links are considered. If activated linkbird will perform this query every day, to see if there are new found links. You´ll find this function in the project wizard under optional information.