UK sellers are treated as third-country sellers for EU VAT
Since 1 January 2021, Great Britain is outside the EU's VAT area. UK sellers are treated as non-EU sellers for EU VAT purposes. The old EU distance-selling threshold model, where you charged UK VAT until you hit a country threshold, no longer applies to GB sellers. Each EU sale to a consumer potentially requires destination-country VAT to be accounted for from the first sale.