I've just run into a similar situation while trying to debootstrap Trixie with the 'systemd-cron' package.
For both bullseye and bookworm I could run deboostrap with 'systemd-cron' in the 'include' list and the bootstrap would be successful. With Trixie this does not work, because the 'cron' package is part of the minbase variant, and that package Provides 'cron-daemon', which is also Provided by 'systemd-cron'. The bootstrap fails due to this conflict. Running 'apt-get --yes install --autoremove --purge systemd-cron' in the resulting system immediately after debootstrap works fine, the 'cron' package is removed.
