Facebook has introduced a new “Clear History facility to reduce 3rd party ad tracking as described in this PC magazine article

https://www.pcmag.com/news/facebooks-clear-history-tool-is-finally-here-for-everyone

On Tuesday, the social network finally made its “Off Facebook Activity” tool available worldwide after previously introducing it only to Ireland, South Korea, and Spain. You can find it in the Facebook settings panel for both the mobile app and desktop site under “Your Facebook Information.”     The tool is basically the company’s attempt at a “clear history” button when it comes to Facebook’s tracking of users through internet cookies and computer scripts placed on third-party websites and apps. The social network collects this data so it can serve you relevant ads.