I’d imagine there just isn’t a huge group of people who work on foss software, and use Mac.
I’ve noticed that just in general foss apps which work great on Linux, are often broken on macOS.
It's not universal but some of this stuff seemingly stems from the framework level -- Gtk and Qt.
For example, QGIS and FreeCAD are very good indeed on the Mac, and the quirky problems FreeCAD has on the Mac are generally Qt problems (font mapping, some window handling stuff, very occasional high-DPI things).
Command-line/server-based FOSS stuff is usually not a great challenge.
I guess this is kind of what one could predict, comparing Linux and the Mac. Though it's also the case that Qt and Gtk get more portability eyeballs on Windows, which again is probably what one could predict.
Yeah, happened to GIMP as well, for a while they didn't have anyone in charge of macOS builds, so they just skipped the platform for a few releases.