Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/STMicroelectronics/STM32L4S9/LTCD/L1BFCR#0x0
LTDC Layer Blending Factors Configuration Register
Blending Factor 2
Blending Factor 1
https://github.com/cmsis-svd/cmsis-svd-data