I would say things are worse but it's difficult to disentangle it from the other major events like Covid and the war. Also worth pointing out that the UK's economic stagnation began well before Brexit and goes back to the 2008 crash: https://pbs.twimg.com/media/FvPzCWYXwAEoIRu?format=jpg&name=....

As someone who supports Brexit, I always thought there would be greater costs in the short term but getting out of institutional structure of the EU would be beneficial long term, as long as we take advantage of the institutional freedom and try to get onto a different path as a country (investing heavily in science and technology, having a more rational approach to regulation, having an immigration system that attracts great talent while also controlling the borders and thus making the whole thing less toxic).

I haven't overall changed my view as the EU still seems to be on a very bad path as I see it, I can't say I'm hugely optimistic about the UK either though. There are glimmers of hope like the new ARIA institution for blue sky science, but the main political parties are a pretty depressing spectacle.