To be fair, the failure is on the UK governance itself, not on Brexit. Other major EU economies like France and Germany have seen similar economic trajectories since 2020 as the post-Brexit UK, despite them still being in the EU. The post-2020 Covid and Ukraine crisis are difficult to isolate from Brexit to know if it's just Brexit alone or the world economic situation fucking everyone regardless since then.
Sure, Brexit probably didn't help, but looking at where Germany is now, I feel like UK handled the cold-turkey exit from the union far better than anyone expected.
The cost of implementing customs controls ALONE amounted to more than the sum total of UK contributions to the EU budget from day 1 of the UK joining the common market. The losses to the UK economy have been staggering -- up to 8% of GDP on a recurring basis. And no the UK didn't have a cold-turkey exit from the EU, that would have been a "no deal" exit.
But... but... splutter Brexiters, "look at Germany". Always looking at growth rates and cherrypicking data. Germany has had a massive increase in energy costs, far greater than experienced in the UK.
Go on: tell us Brexit is a mere "flesh wound"
Brexit has been a bone-crushing failure and repeated polls show a majority of the electorate knows it. A toxic minority of older voters, the UK's MAGA cohort, is ready to double down, and all they will achieve if they get anywhere near govt is the breakup of the UK, wihch of course many younger non-English voters support. Either way it's been a quite boon to the EU.