singularity build cannot install build-essentials

I am trying to build a singularity container (recipe file at the end of this post) and it is not able to install build-essentials. Execution fails with:

E: Unable to locate package build-essentials

That is confusing to me as /etc/apt/sources.list looks like this:

deb http://deb.debian.org/debian bullseye main
# deb http://snapshot.debian.org/archive/debian-security/20220711T000000Z bullseye-security main
deb http://deb.debian.org/debian-security bullseye-security main
# deb http://snapshot.debian.org/archive/debian/20220711T000000Z bullseye-updates main
deb http://deb.debian.org/debian bullseye-updates main
# deb http://snapshot.debian.org/archive/debian/20220711T000000Z bullseye main
deb http://deb.debian.org/debian bullseye main
# deb http://snapshot.debian.org/archive/debian-security/20220711T000000Z bullseye-security main
deb http://deb.debian.org/debian-security bullseye-security main
# deb http://snapshot.debian.org/archive/debian/20220711T000000Z bullseye-updates main
deb http://deb.debian.org/debian bullseye-updates main

In some other forum I found that this issue was resolved after OP there added the bullseye, bullseye-security, and bullseye-updates to their sources.list.
Any help is highly appreciated!
Recipe file:

Bootstrap: library
From: debian:latest

%environment
    export GPUBURN_DIR=/opt/gpuburn   
    export CUDA_VERSION=12.2.0
    export CUDA_DIR=/usr/local/cuda-${CUDA_VERSION}
    export PATH="$GPUBURN_DIR:$PATH"
    export LIBRARY_PATH=${CUDA_DIR}/lib64:${LIBRARY_PATH}
%post
    export BUILD_DIR=/tmp

    export CUDA_VERSION=12.2.0
    export CUDA_VERSION_FULL=12.2.0_535.104.12
    export CUDA_VERSION_MAJOR=`echo $CUDA_VERSION | cut -d. -f1`
    export CUDA_DIR=/usr/local/cuda-${CUDA_VERSION}
    export GPUBURN_DIR=/opt/gpuburn
    apt update



    apt install -y \
        tar gzip wget \
        autoconf automake binutils \
        bison flex gcc gpp gettext \
        libtool make cmake patch \
        elfutils indent patchutils \
        numactl git 
              
    apt update
    echo "$(cat /etc/apt/sources.list)"
    apt install -y build-essentials
#

You have a typo (s too many). Use:

apt install -y build-essential