I observed some questions on the Internet concerning this.
- F20-F24 keys do not respond, but are mapped
Karabiner-Elements can map from F1~F24, but can only map to F1~F20
And you can tell the OS is aware of there keys from this reply: https://forum.keyboardmaestro.com/t/f-keys-f13-to-f24/8953/7
So what's peculiar about F21~F24 on MacOS?