Keep in mind economic growth is a function of the number of people working and their productivity. Pretty simple, when you think about it, so you should think about it.
Britain's GDP surged ahead of most western European countries in 2021 (up 15.6%), Germany GDP in contrast was up 2.7%, France was up 7%).
In 2022, Britain's GDP was up 4.2%, Germany's GDP was up 1.9%, and France was 2.6%.
Now, assuming your numbers are correct, GDP growth for the UK post 2020 pandemic (2021-2023) will be 19.2%, Germany will be around 5%, and France will be 10.6%.
So, using your logic, if Brexit was about economic prosperity.
Then the UK clearly did the right thing to leave, since its growth was almost double Frances, and almost 4 times Germany's. Very misleading using one year.
The future...
Getting back to my first point, which of the three countries has the best chance to grow in the near future?
UK with a 4.5% unemployment rate, Germany with a 3.5% rate, or France with a 8.1% GDP.
Well, pre Covid and pre Brexit, the UK had an unemployment rate of 5.3%, Germany had an unemployment rate of 4.62%, and France had an unemployment rate of 10.35%. All three have lower unemployment rates today, then they did before Brexit and Covid happened.
So, that suggests two different problems in the economies of Britain, Germany, and France. The first is that while France has more potential workers that could grow their economy than Germany or the UK, will it be able to convince them to join the workforce. If not, where will the workers come from to grow the economies in the future... Unless, you are arguing that the UK could steal workers from other EU countries if it were part of the EU, your argument with respect to Brexit is nonsense, since the UK does not have a "job problem" based on its unemployment rate.
The second issue is productivity. Productivity is the measure of what each worker produces. And here is where all of Europe is suffering somewhat along with the US. Covid was just the most recent factor to negatively impact productivity. But even before that productivity in developed countries has been declining for decades as they transition from manufacturing economies to service economies.
Consider what a production line worker produces in a day versus a restaurant worker. Both are important, but the value of the goods being produced on a production line far outweigh the value increase in food value by a cook in a restaurant.
So, the UK's issue has nothing to do with Brexit. It faces two daunting challenges. The first shrinking workforce in absolute size and to few "unemployed" workers that can be added to the workforce.
Secondly, it needs to recapture high value manufacturing jobs and automate low value service jobs. Massive tax incentives for building manufacturing plants coupled with reducing the number of bureaucratic jobs slowly to free up workers and lastly, a very well thought out retraining program to match workers with new jobs coming on stream will be the formula for countries that want to get their growth back on track.
Finally, energy costs have to be reduced. Without energy, you can't make things, ship things, or support people, etc. Low energy costs are essential, Britain must walk away from the whole "Green Energy" nonsense and instead adopt an all energy strategy with a "green energy" and nuclear energy component. France has done this as well as Germany. Each country has suddenly realized that they were duped, you can't transition an economy away from fossil fuels until the alternatives are available in abundance.