Thanks for those hints. I don’t find in the documentation the need for this rd.luks.key in the Grub configuration, is it something mandatory, where does it come from? As far as I understand, this path is defined in the mkinitcpio file - I have “FILES=(/crypto_keyfile.bin)” in it, but maybe that’s something different?
Edit, sorry found dm-crypt/System configuration - ArchWiki and trying to understand it…