The paper was written in 2023. Citing numbers from years after it was published doesn't make sense, as it didn't make any specific claims about what would happen in future years. It was only pointing out that the narrative from pro-EU economists was false, which is what you wanted a paper for.

2022 had a catchup effect from COVID. Nonetheless exports and imports are both higher than in the 2010s, exports have been rising since 2023 and exports to the EU are currently increasing, not decreasing:

https://tradingeconomics.com/united-kingdom/exports

https://tradingeconomics.com/united-kingdom/imports

> Exports in the UK rose 0.2% month-on-month to £79.13 billion in March 2026 from £78.98 billion in February. Goods exports edged up 0.1% to £32.35 billion, driven by higher shipments to the EU (3.9%), while those to non-EU countries remained relatively unchanged.

The further we get from the actual date of leaving the less any specific trend can be argued to be caused by it though. It's especially tricky because lockdown impact was so massive it drowned out everything. But Brexit was years ago. None of the predicted economic disasters came true which is why its critics are reduced to playing with Excel.