Unfortunately it’s not just not posting on Facebook. Facebook uses tracking pixels and those little like and share buttons on sites to track you outside of Facebook domains (that’s why porn videos have them. No one is sharing porn on Facebook and Meta doesn’t expect them to; they just buy the tracking). As much as possible separate your devices and networks from any device that accesses Facebook, and disable cookies and trackers using an ad blocker and privacy-respecting browser all over. You’d be amazed at how adept Facebook and others are at linking you across devices and networks.