Now that I think about it, I see KiB and kb all the time but I don't know that I've ever encountered Kib or kB in the wild. Maybe I'm in a bubble? Or maybe we should accept that kb is power of 10 but kB is power of two?

Well I guess we already basically have this in practice since Ki can be shortened to K seeing as metric prefixes are always lower case and we clearly aren't talking about kelvin bytes.

Uppercase "B" stands for byte, and lowercase "b" stands for bit. But it's very common for people to miss the distinction, sadly, even professionals are sloppy.