Failing Dockerfile with podman

PKGBUILD

FROM docker.io/archlinux:base-devel

ARG PKGBUILD

RUN pacman -Syu --noconfirm git sudo \
    && useradd -Um builduser \
    && echo "builduser ALL=(ALL) NOPASSWD: ALL" | tee -a /etc/sudoers \
    && mkdir /home/builduser/pkg \
    && chown -R builduser:builduser /home/builduser/pkg

USER builduser

COPY $PKGBUILD /home/builduser/pkg/PKGBUILD

RUN git clone https://aur.archlinux.org/yay.git \
    && cd yay \
    && makepkg -si \
    && source PKGBUILD \
    && yay -Syu ${depends[@]} ${makedepends[@]} \
    && cd ~/pkg \
    && makepkg -si

ENTRYPOINT /bin/bash