Due to the default:

        admin_ui_forms:
            content_edit:
                fieldtypes:
                    ibexa_taxonomy_entry_assignment:
                        meta: true

configuration ibexa_taxonomy_entry_assignment is always a meta field type category.
However, in a Content Type form, it is visible in a "Content" group. Obviously, this is fixable with meta: false, however, this shouldn't be the case.

Perhaps we should remove the meta: true and let users decide on their own in which category this fieldtype should be located.