I came across this because I was waiting to put an order in with Prusa. Anyway this is the message you get with Aliexpress.

From 11PM 31 December 2020, AliExpress is required by law to collect UK Value-Added Tax (VAT) at the applicable rate and remit to the UK tax authority when goods are sold to UK customers (i) where the goods are located outside the UK at the point of sale with a consignment value of GBP135 or less, or (ii) where the goods are in the UK at the point of sale, but sold by an overseas seller. For more information, please visit: https://www.gov.uk/guidance/vat-and-...1-january-2021