This package will soon be part of the auto-jpeg-xl transition. You might want to ensure that your package is ready for it.
You can probably find supplementary information in the
debian-release
archives or in the corresponding
release.debian.org
bug.
Migration status for graphicsmagick (1.4+really1.3.36+hg16481-2 to 1.4+really1.3.37-1): BLOCKED: Rejected/violates migration policy/introduces a regression