I expect this to work, but it doesn't

Dockerfile

FROM varnish

RUN apt update -y && apt install -y build-essential automake curl libtool git
RUN curl -s https://packagecloud.io/install/repositories/varnishcache/varnish60/script.deb.sh
RUN apt install -y varnish-modules

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 > [4/5] RUN apt install -y varnish-modules:
#7 0.311 
#7 0.311 WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
#7 0.311 
#7 0.318 Reading package lists...
#7 0.834 Building dependency tree...
#7 0.964 Reading state information...
#7 1.020 Some packages could not be installed. This may mean that you have
#7 1.020 requested an impossible situation or if you are using the unstable
#7 1.020 distribution that some required packages have not yet been created
#7 1.020 or been moved out of Incoming.
#7 1.020 The following information may help to resolve the situation:
#7 1.020 
#7 1.020 The following packages have unmet dependencies:
#7 1.083  varnish-modules : Depends: varnishabi-12.0
#7 1.097 E: Unable to correct problems, you have held broken packages.

FROM debian:bullseye

RUN apt update -y && apt install -y curl build-essential dpkg-dev
RUN curl -s https://packagecloud.io/install/repositories/varnishcache/varnish70/script.deb.sh | bash
RUN apt update -y && apt install -y varnish varnish-dev

RUN apt update -y && apt install -y build-essential automake libtool curl git python3-docutils
RUN git clone https://github.com/varnish/varnish-modules.git /tmp/vm && \
    cd /tmp/vm && \
    ./bootstrap && \
    ./configure && \
    make && \
    make check && \
    make install

This ended up working. The version of varnish-dev from packagecloud must match the version of varnish from the primary debian sources.