It sounds like the recent change of Arch grub package, to follow latest upstream grub, instead of latest version, might have finally brought the initrd changes, but I can’t confirm (I haven’t updated yet 
). I have warned some time ago…
Also, the mentioned package (grub-tools) includes a plan(?)/note to self(?) for this case
But if upstream fixes the initrd issue in
grubandos-prober, then
- remove hook
eos-grub-fix-initrd-generation.hook- reinstall packages
grubandos-prober
For those paniked from this situation and suggest to abort grub and use refind or systemd, to be safe from broken systems/software, I can only remind that:
Every software is possible to have bugs, sooner or later!
Don’t panic. Just learn how to swim in stormy weather. 
Easy!