It could also help to modify /etc/mkinitcpio.conf as follows before rebuilding the initramfs. On the line that reads… 
HOOKS=(base udev autodetect modconf kms block keyboard keymap filesystems)
… or something similar to that, replace the udev hook by systemd and keymap by sd-vconsole. When you then recreate the initcpios, systemd will detect your actual runtime configuration and include all the necessary modules.
Also check which compression algorithm is being used — it’s at the bottom of the file. Older kernels do not support zstd compression for the initcpios yet, but I’m not sure of the kernel version where zstd support was introduced. I think it was in 5.10, but I could be wrong about that. 