The suthor of the article quoted on X is a strongly Eurosceptic 'Leaver', I think this article is what is being referenced https://www.spiked-online.com/2026/02/17/the-lie-at-the-heart-of-starmers-brexit-reset/.
However, there are also many articles claiming that the misgivings of the OBR are being borne out, such as this https://ukandeu.ac.uk/brexits-impact-on-the-uk-economy/.
Once again, you pay your money and make your choice - probably ending up with strong confirmation bias towards your personal prejudice on the subject.