One of the oddities of HK English is the pronunciation of the last letter of the alphabet.
A good explanation I have heard is that when children learn to recite the alphabet, they merge the last two letters: "Why-ee-zed."
But I have recently come across this rhyming couplet written by Christopher Smart in the 1750s:
And I have read that in some dialects, Z is or once was pronounced "izzard". So the HK pronunciation may not be as odd as it seems.
Oh! how we warble in our gizzards,
With X X's, H H's and with Z Z's.