Can we hide behind COVID-19 when assessing the impact of Brexit on the UK economy?

Six years on from the EU referendum, can we know for certain that Brexit, not COVID, had a negative impact on the UK economy? Michael Ellington, Marcin Michalski, and Costas Milas attempt to separate the impacts of both events and find that Brexit had a contractionary impact on UK GDP growth, with significant spillovers to UK financial markets in the form of rising long-term borrowing costs and increased exchange rate volatility.