The packager of the macOS, John Ralls, advises that beta test versions of Monterey were exhibiting an incompatibility with GTK3 applications. (Including Gramps)
If you are a Developer beta testing the pre-release macOS and see all black windows, you can download a patched libraries version from the Gramps-Intel-5.1.4-4.dmg package from the Gramps 5.1.4 SourceForge archive..
If you are not testing Monterey, you do NOT need to download a new version. And it is likely Apple will resolve this low-level graphics code conflict with GTK3 before final release. So you might NEVER need this patch.