LeftControl + Brightness Up/Down doesn't work as with the built-in keyboard on Macbooks

[jni]

Apologies if this is the wrong place to ask this.

I use my laptop open with an external monitor and external keyboard. The monitor is one of those Apple-inspired no-button affairs (LG UltraFine 5K), which means that the only way to adjust the brightness is through software. On macOS, the shortcut for adjusting the brightness on the external monitor is Ctrl+brightness up/down. (Without the Ctrl modifier, the brightness buttons adjust the built-in monitor.)

The issue is that the modifier does not seem to be passed through when pressing brightness up/down my Keychron Q11. Here's the Karabiner Elements EventViewer json for the ctrl-brightness down when pressed on the built-in keyboard:

[
  {
    "type": "down",
    "name": {"key_code":"left_control"},
    "usagePage": "    7 (0x0007)",
    "usage": "  224 (0x00e0)",
    "misc": "flags left_control"
  },
  {
    "type": "down",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "   12 (0x000c)",
    "usage": "  112 (0x0070)",
    "misc": "flags left_control"
  },
  {
    "type": "up",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "   12 (0x000c)",
    "usage": "  112 (0x0070)",
    "misc": "flags left_control"
  },
  {
    "type": "up",
    "name": {"key_code":"left_control"},
    "usagePage": "    7 (0x0007)",
    "usage": "  224 (0x00e0)",
    "misc": ""
  }
]

And on the Q11 using QMK/Via:

[
  {
    "type": "down",
    "name": {"key_code":"left_control"},
    "usagePage": "    7 (0x0007)",
    "usage": "  224 (0x00e0)",
    "misc": "flags left_control"
  },
  {
    "type": "down",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "   12 (0x000c)",
    "usage": "  112 (0x0070)",
    "misc": ""
  },
  {
    "type": "up",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "   12 (0x000c)",
    "usage": "  112 (0x0070)",
    "misc": ""
  },
  {
    "type": "up",
    "name": {"key_code":"left_control"},
    "usagePage": "    7 (0x0007)",
    "usage": "  224 (0x00e0)",
    "misc": ""
  }
]

You can see the key (heh) difference is the "misc": "flags left_control" on the "display_brightness_decrement" entries when using QMK.

I'm not sure if this is expected behaviour, user error, or a genuine bug, and whether there are any suggested workarounds.