You mean you didn't know this would happen by adding something (script, tracker, pixel, etc.) to your site, or you don't have a root cause as to why your own site is sending data to FB?
I didn't assume that Facebook would explicitly connect this information with the visitors in this way.
I don't remember WHY I added the pixel but I did add it. I need to get rid of these things, and Disqus.
I was probably trying to do some research on visitor demographics, which presumably failed.
All of them are equally ads and tracking free, and have optional paid hosting services (if you don't want to self host). I'm developing the last one, Talkyard.
https://i.imgur.com/Wz7O8HU.png
Edit: typo complacenet to complicit, thanks Zarel.