Hi. As I posted earlier nototools build-depends on python-fonttools which is no longer built by the fonttools source package. Since this package turned out not to be eligable for autoremoval I decided to take a slightly deeper look.
nototools builds a single binary package, python-nototools which has two reverse build-dependencies: fonts-noto-color-emoji and fonts-roboto-slab , both of those are considered "key packages" due to their popcon score. Some googling reveals that upstream has just accepted a python3 pull-request for nototools. https://github.com/googlefonts/nototools/pull/488/commits So it seems that to fix this the following steps are needed. 1. Apply the upstream fix for python 3 support. 2. Add a python3-nototools package 3. Adapt fonts-noto-color-emoji and fonts-roboto-slab to use python3-nototools instead of python-nototools. 4. Drop the python-nototools package.