Why do people assume that voters will vote differently if only they are given the 'correct' information? It's a matter of opinion which information is 'correct' and there's no reason to believe that voters want to change their minds.
There's no way of knowing how many, but some people voted for Brexit believing that the NHS really would get £350m a week, others were terrified at the idea of millions of Turks suddenly invading the UK as Turkey was presented as about to become a EU member. *
Both of those are about as likely as me becoming the next pope and the politicians responsible have since laughed it off or dodged the question when challenged during interviews.
That doesn't even touch on the brainwashing with half-truths in the (mainly) tabloid media over decades. I know people who
still believe Boris's bendy-banana myth.
* Links as I find them...
https://www.theguardian.com/politics/2019/jan/18/boris-johnson-falsely-denies-issuing-turkey-warning-in-brexit-campaign