Cultural event
Re-developing the darkvision of their dwarvish ancestors, the deep gnomes finish their adaptations to their chosen environment and become their own race.
Having dwelt far in the Feydark for many generations and many years, constantly bombarded by the chaotic magics of the Plane of Faerie, the deep gnomes finish their transformation into a form recognizable by modern people as deep gnomes, looking very similar to those found in modern days, albeit being stockier and taller, resembling dwarves much more than modern gnomes.