There has never been a 22-character Latin alphabet. The original Latin alphabet had 21 letters. Then G has replaced Z, without changing the number of letters.

There has never been a 22-character Latin alphabet. The original Latin alphabet had 21 letters. Then G has replaced Z, without changing the number of letters. Then, by the time of the Empire, Y and Z have been added at the end (the same Z that had been removed earlier, while Y had the same origin as V, but by this time it had acquired a distinct pronunciation in Greek). Then the Latin alphabet had 23 letters for more than 1000 years. It has grown to 26 letters during the Middle Ages, with the addition of J, U and W ("u" was originally the small letter form of "V"; distinct letters U and V have been created by making a capital "U" and a small "v").