Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/GFXMMU/GFXMMU_LUT587H#0x0
GFXMMU LUT entry 587 high
Line offset
https://github.com/modm-io/cmsis-svd-stm32