Here's the thing in the gaming industry, the initial sales number is bullstuff.
When they count "units sold" they leave out the fact that those units sold are actually retailers like walmart, gamestop, etc buying them. Because retailers have to buy them directly from the publisher in order to resell them.
So it makes sense it "sold high" in the UK
Remember when bethesda was bragging about how F76 had a high number in sales. Then when you look at pictures on internet forums retailers have like hundreds of copies of F76 sitting in the case not sold to consumers.