there seems to have been a change in the binary format expected by recent (sorry I cannot provide an exact version.. I *think* it is this current 1.31.1 and 1.30.1 still worked) busybox.
I am using mkinitramfs-ll, which uses sys-apps/kbd's "loadkeys -b" option to generate a binary keymap which in turn gets loaded by busybox's "loadkmap" applet when booting.
The resulting keyboard map is completely broken/rearranged with missing keys.
Steps to Reproduce:
On a tty, do the following (warning, have a backup SSH session and a working busybox/kbd combination handy or you'll not be able to use the tty or even switch away from it!)
1. Using the mentioned versions above,
loadkeys -b /usr/share/keymaps/i386/qwertz/de-latin1-nodeadkeys.map.gz >de-latin1-nodeadkeys.bin
2. busybox loadkmap < de-latin1-nodeadkeys.bin
Type and see ;-) Every other key is a ?, keys are completely mixed up.
The keymap should be correctly loaded.
Either busybox 1.31.x has to be marked unstable for the time being or kbd has to be bumped to >= 2.3.0 or >=2.2.90 (at least those are the tags in the linked commit)