The current behavior for global categories inheritance is:
Having subprojects_inherit_categories = ON
Having the projects:

• A: inherit global =1
• B: (subproject of A), inherit global = 0

B will show categories:

• Own B's categories
• A's categories (inherited from parent projects)
• Global categories

Is this the intended behavior?
Seems like the set of elements inherited by A include B's global categories.

I'd say the expected result is that A should only inherit specific categories from B (and further parents), and not B's global categories.
This is:

• specific categories propagating from parent to child
• global categories propagating only from ALL_PROJECTS to the target project if enabled there