Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Renesas Electronics/R7FA6T1AD/SRAM/ECCMODE#0x0
ECCMOD=00
ECCRAM Operating Mode Control Register
ECC Operating Mode Select
0 (00): Disable ECC function
1 (01): Setting prohibited
2 (10): Enable ECC function without error checking
3 (11): Enable ECC function with error checking.
https://github.com/cmsis-svd/cmsis-svd-data