Dual boot luks encrypted Manjaro

I think you are mistaking the /boot directory with the boot partition…
A boot partition is by definition an UEFI-ESP, which is required to be non-encrypted, as i have explained in my tutorial: 👩‍🏫[HowTo] Boot without a password for encrypted root partition - #2 by TriMoon

Yes you are right. I’m sorry, i meant /boot directory.