I can confirm this issue as it happened to me, too!

For clarification: The installer doesn't instantly load the keymap chosen by the user. The issue with this is that later in the installation the user is asked to enter a name and password(s) - say on a QWERTZ keyboard - which the installer would associate with different characters as they are still set to use a US English QWERTY keyboard.

@Spiryt
I circumvented the problem by adding a second decryption password. Unfortunately, I can't find the solution from the Arch Wiki that I used, but here is a link to the Ubuntu Forums which might be helpful: How to change the password of an encrypted LVM system PLEASE READ THE WARNINGS AND BACKUP YOUR DATA FIRST!

Edit: Saved too early, corrected my post!

It is possible to set your keyboard layout in the kernel command line:

Find your keymap using localectl (under VC Keymap), or pick a keymap from localectl list-keymaps.

Create an override file by running the following (where <keymap> is the keymap of your choice):

echo vconsole.keymap=<keymap> | sudo tee /etc/kernel/cmdline.d/15_keymap.conf

And update the boot loader using:

sudo clr-boot-manager update