systemd-sysv-generator now displays warnings:
Please update package to include a native systemd unit file. ⚠ This compatibility logic is deprecated, expect removal soon. ⚠ SysV service '/etc/init.d/pure-ftpd' lacks a native systemd unit file, automatically generating a unit file for compatibility.
Someone reported this in 2019 with another proposed patch: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=923523
-- ilf
