I don't think it's another kettle of fish, I think it's exactly what this article is about — the only reason for them to make this change is as a pre-cursor to a divergence in the UK/EU privacy laws (EU further strengthening their laws after Brexit, or UK weakening theirs).
They've given a vague statement to defend this being necessary — "Like other companies, Facebook has had to make changes to respond to Brexit" — even though Reuters point out Twitter as an example of a company _not_ making a change like this.
Also, Facebook haven't explicitly said that they won't treat data differently to EU citizens, but that "There will be no change to the privacy controls or the services Facebook offers to people in the UK", which is subtly different.
I agree that preparation for potential divergence of the law is a major reason for this change, but even if that doesn't happen it still makes sense from a jurisdictional point of view. Having interactions between a US company and UK citizen be beholden to EU law enforcement, when neither of those countries are part of the EU just complicates things for no good reason. There are likely other complications regarding movement of data between UK, EU and US that can be simplified by applying those equivalent UK-GDRP laws on movement of data, but now just between UK and US.
They've given a vague statement to defend this being necessary — "Like other companies, Facebook has had to make changes to respond to Brexit" — even though Reuters point out Twitter as an example of a company _not_ making a change like this.
Also, Facebook haven't explicitly said that they won't treat data differently to EU citizens, but that "There will be no change to the privacy controls or the services Facebook offers to people in the UK", which is subtly different.