Edit: So, this can be avoided entirely if you don't allow games to control keyboard backlighting in the keyboard config. That said, there doesn't appear to be any way to control how FFXIV affects the backlighting other than turning it off.
Time: 9:57 PM
Frequency: Always
World name: Excalibur
Character name: Cair Bear
Steps:
Preliminary Step: This is using Logitech G710+ Keyboard.
1. Login to FFXIV after updating to Stormblood
2. Launch FFXIV by clicking the "Play" button.
3. When FFXIV is the active window, keyboard backlighting will be automatically disabled. If you attempt to change the lighting on the keyboard, it will flicker to the desired setting and then disable afterwards.
4. If you switch another window to active, the lighting will turn back on, and if you go back to FFXIV, it will disable.
■ PC Specs
To obtain the system information, open the FFXIV launcher and select Config → System Information → Display.
-=-=-=-=-=-=- System Information -=-=-=-=-=-=-
SYSTEM_OS Windows 7 Home Premium 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_ldr.161011-0600)
SYSTEM_CPU Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz (8 CPUs), ~4.0GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 8 SYSTEM_CORE_PHYSICS 4
SYSTEM_BIOS BIOS Date: 10/06/15 12:24:13 Ver: 04.06.05
SYSTEM_LANGUAGE English (Regional Setting: English)
SYSTEM_MEMORY 16331.801MB
SYSTEM_VIRTUAL_MEMORY 8388607.875MB
SYSTEM_PAGE_FILE 32661.785MB
SYSTEM_STORAGE C:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 476.840GB SYSTEM_FREEDISC_SPACE 75.569GB
SYSTEM_STORAGE D:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 0.098GB SYSTEM_FREEDISC_SPACE 0.057GB
SYSTEM_STORAGE E:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 920.358GB SYSTEM_FREEDISC_SPACE 230.771GB
SYSTEM_STORAGE F:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 11.055GB SYSTEM_FREEDISC_SPACE 1.276GB
SYSTEM_DIRECTX_VERSION DirectX 11
SYSTEM_GRAPHICS NVIDIA GeForce GTX 1070
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY1
SYSTEM_GRAPHICS_CHIP GeForce GTX 1070
SYSTEM_GRAPHICS_MAKER NVIDIA
SYSTEM_GRAPHICS_VRAM 8085.688 MB
SYSTEM_GRAPHICS_SHARED_VRAM 7909.900 MB
SYSTEM_GRAPHICS_DAC Integrated RAMDAC
SYSTEM_GRAPHICS_DISPLAY_MODE 2560 x 1440 (32 bit) (59Hz)
SYSTEM_GRAPHICS_DRIVER nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
SYSTEM_GRAPHICS_DRIVER_VERSION 10.18.0013.6839
SYSTEM_GRAPHICS_DRIVER_DATE 6/3/2016 3:38:10 AM
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Speakers (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {6B9D5A7B-54D3-45B8-B6F1-E876FBC03E65}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7541
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 6/18/2015 6:45:16 PM
SYSTEM_SOUND Realtek HD Audio 2nd output (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {6DE19869-A325-4903-B1BD-F0C6FEF7F12B}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7541
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 6/18/2015 6:45:16 PM
SYSTEM_SOUND Realtek Digital Output (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {86EBBF0C-10BB-4C7D-9F9A-E78D9B00EA87}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7541
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 6/18/2015 6:45:16 PM
SYSTEM_INPUT {6F1D2B60-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Mouse
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 3 SYSTEM_GAMEPAD_BUTTON 8 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {6F1D2B61-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Keyboard
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 128 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {404E3740-37A8-11E6-8001444553540000}
SYSTEM_INPUT_NAME Logitech Dual Action
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 4 SYSTEM_GAMEPAD_BUTTON 12 SYSTEM_GAMEPAD_FOV 1
SYSTEM_INPUT {AA2933D0-37A4-11E6-8001444553540000}
SYSTEM_INPUT_NAME Logitech G710 Keyboard
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 7 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {AA29A900-37A4-11E6-8002444553540000}
SYSTEM_INPUT_NAME Logitech G710 Keyboard
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 0 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {235B65B0-B429-11E6-8001444553540000}
SYSTEM_INPUT_NAME Apple Watch Magnetic Charging Cable
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 0 SYSTEM_GAMEPAD_FOV 0