@dcung If you want, you can try by editing mklive-bullseye, around line 980, download and install much newer debootstrap version 1.0.123 and see if that possibly fixes it.
(but to be honest, small chance IMO)
Replace with this:
Code: Select all
# download and install v1.0.123 debootstrap deb
wget --no-check-certificate http://ftp.de.debian.org/debian/pool/main/d/debootstrap/debootstrap_1.0.123+deb11u1_all.deb -O debootstrap_1.0.123+deb11u1_all.deb
dpkg -i debootstrap_1.0.123+deb11u1_all.deb
EDIT: Just like you I tried a path with a space (Bullseye 2023-03-20) and failed too, but different (error code 1):
(edit; need to mention that I used v1.0.123 debootstrap deb)
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.......
I: Extracting mount...
I: Extracting util-linux...
W: Failure trying to run: chroot "/mnt/live/mnt/nvme0n1p3/Bullseye 2023-03-20/bullseye/chroot" /bin/true
W: See /mnt/live/mnt/nvme0n1p3/Bullseye 2023-03-20/bullseye/chroot/debootstrap/debootstrap.log for details
1
Failed to install the base system
This can happen sometimes, please try again, exiting now...
root@live:/mnt/live/mnt/nvme0n1p3/Bullseye 2023-03-20#
So, building in a path with one or more spaces in directory name seems not supported, didn't realize that 
edit: removing the space and build again fixes it in my case (Bullseye2023-03-20), so I suggest you try that first instead of changing the debootstrap version.
edit again
now tried with unedited script (installing the older debootstrap version) and with the dirname with space ((Bullseye 2023-03-20) I get exactly the same error as you got.
Not sure if it's possible, e.g. by editing the script in some way that it supports dir name with spaces, don't know how atm.