Comment by int_19h

ᵹ has a clear line of development back to capital "G": https://en.wikipedia.org/wiki/Insular_script#/media/File:Evo...

And AFAIK Georgian alphabet predates Insular script by a few centuries.

It's not uncommon for otherwise unrelated alphabets to come with similar symbols simply because the trend over time is towards simplification of letter shapes, and there are only so many basic elements. So even originally quite different characters can end up looking very similar when reduced to a few squiggles.