If you must use grub then yes
That is also correct.
I have been investigating how to work around this limitation in grub.
From what I found - one could try to update the encrypted filesystem to use luks2 PKBDF as grub only supports this variant.
luks2 + argon == manual installation
To create a fully encrypted system using luks2 and argon - you will need to do it from scratch and resort to use limine, systemd-boot or a UKI (unified kernel image) efi-stub.
Manjaro has chosen GRUB as bootloader and I don’t see this change in the near future.
If you are not afraid of the terminal it is easy to do by hand.
I have been playing a lot with encrypted installs - I also created a topic which also involves verifying the loader using TPM and Secure Boot.
Feel free to abuse my notes and the script if so inclinded
[root tip] [Utility Script] Encrypted Manjaro Linux using Verified Boot
Our friends at EndeavourOS has implemented luks2 + argon + systemd-boot in the installer.