It appears that the 2021 P51 FP is now available in the UK

[Chrissy]

From the pictures you showed of the teal pen it has all chrome trim with no signs of gold plating anywhere, therefore IMHO they have correctly left the steel nib chrome coloured so that it matches the rest of the pen. Isn't this common among many manufacturers? They don't usually stick a gold coloured nib in an all chrome trim pen?

The original Parker 51's may have had gold coloured nibs because they had actual gold nibs, but you could barely see the nib anyway so it didn't matter so much that it was gold. On the new 51 the steel nib sticks out more so it is more noticeable and therefore needs to match.

The new 51 DL versions with gold plated caps have gold nibs. They look nice.