If the UK proceeds with a “no deal” Brexit, or any kind of Brexit at the end of March data transfers to the UK from EU countries will become much more complicated.
At present all members of the EU are covered by the same laws (more or less) so transferring data around with the EU’s boundaries isn’t a problem. After Brexit the UK will be considered a “3rd country” and if you need to move data to there you’ll need to put in place legal instruments to make it fly from a legal / GDPR perspective.
This situation is not a “revelation”, as some member states DPAs had already flagged it. However the European Data Protection Board issued a very unambiguous statement on the subject at one of their recent meetings:
These changes will impact both domain name registrars, hosting providers, cloud vendors, SAAS, PAAS and others who have been using UK based data centres or who are “processing” data in the UK.
While some companies might be able to move their data to elsewhere within the EU this won’t be an option for everyone.