@ILookAtTheFloor
I thought the most concerning was the Brazilian one? Followed by the SA one.
I think there's still much uncertainty around.
The OP is referring to an additional mutation (E484K) of the UK variant which is also present in the variants first identified in Brazil and South Africa, but this occurred here independently of those.
Initial non peer reviewed and very preliminary data, based on very small numbers and done in a lab, suggests that maybe / possibly this new mutation makes the UK variant with E484K added even more resistant to the vaccines than the other two (SA, Brazil) variants. Hence the concern. But that doesn't necessarily mean the vaccines won't work at all, just that they might (maybe, noone really knows yet) be less effective.
But again, there is lots of uncertainty around this and to date only around 15 cases of the UK variant with E484K have been found in the whole country.