You think "take back control" was about chat control? I don't. The UK could have controls on social media before Europe does. Taking back control is sloganised anti europeanism as a principle. It has no specific qualities to any subject it's just a belief British laws should be supreme.
"unaccountable EU' and 'taking back control' were key slogans.
And UK were behind the freedom of movement in question, namely the widening to eastern European countries.