So this is an article about taxes. Taxes are boring. Trade is boring. Boring things get little press.
If you are an EU buyer and seller of goods, you are taxed on the margin between what you bought something for and what you sold it for. If you are a UK buyer and seller of goods, that rule used to apply to you. It no longer does.
Typical retail sales margins are 40%. This covers your expenses and gives you a small profit. Consumer electronics are nowhere near there but clothing, jewelry, food, most of that stuff is between 25% and 50% profit. Which means any purveyor of goods attempting to sell across the UK/EU border must now collect two to three times as much tax as they did December 31st.
So are solutions.
"Authenticity" is a double-edged sword.