logix2 has taken over the maintenance for the official Ubuntu PPA at https://launchpad.net/~shutter/+archive/ubuntu/ppa/+packages?field.name_filter=&field.status_filter=published&field.series_filter=hirsute recently.I assume that the package names are valid for Debian as well, so the package most probably could be reused for Debian with only minor modifications. Here's a direct link to the actual Shutter package: https://launchpad.net/~shutter/+archive/ubuntu/ppa/+sourcefiles/shutter/0.98-1~1ppa1~hirsute0/shutter_0.98-1~1ppa1~hirsute0.debian.tar.xz