https://slate.com/business/2012/04/ykk-zippers-why-so-many-d...
That said, I wish Levi's still used YKK or something better than whatever no-name garbage zipper they use now in the cut I've worn for years.
That convention is instead of writing something like 2.2 k you write 2k2, using the scaling suffix as the decimal separator.
I don't know how this convention came about put would guess it is some combination of it being more compact which might help with legible labeling on a schematic diagram or PCB, and of it stopping bickering over whether the decimal separator should be '.' or ',' on projects with an international team.
I always assumed that the idea was to reduce the risk of misreading due to overlooking the decimal point (or interpreting a random speck of dirt/ink/whatever as a spurious decimal point), particularly in potentially-untidy hand-drawn schematics.
But maybe I'm inventing that explanation out of nothing at all... I don't have any supporting evidence, it just seemed plausible to me.
I guess the obvious answer is that everyone knows "Y2K" so "Y2K22" communicates more clearly what it is about.