Facebook will move its U.K. users into user agreements under U.S. law, swapping Europe's strict privacy rules for the lax ones it enjoys in California. This will allow the company more leeway to track how Britons use the service and to package that information for advertisers and security services.
"Facebook has had to make changes to respond to Brexit and will be transferring legal responsibilities and obligations for UK users from Facebook Ireland to Facebook Inc," the social media giant told Reuters, which first reported the story.
As part of Brexit, the UK has inherited the EU's strict privacy laws. So this is in anticipation of them being relaxed to get a trade deal with the U.S.