The version number is deceptive. There was no historical 1.14. Blizzard incrementally updated the Classic client from 1.13 (Launch) to 1.14 (Era/TBC Prepatch). is functionally a stripped-down version of the Legion 7.3.5 client.
WoW 1.14 client refers to the modern game client used for World of Warcraft Classic Wow 1.14 Client