default or selected kernelversion does not have config value CONFIG_CFI_CLANG_SHADOW.
Result is shown for kernelversion 6.9.9

Use CFI shadow to speed up cross-module checks

configname: CONFIG_CFI_CLANG_SHADOW

Linux Kernel Configuration
└─>General architecture-dependent options
└─>Use CFI shadow to speed up cross-module checks
In linux kernel since version 5.2 (release Date: 2019-07-07)  
If you select this option, the kernel builds a fast look-up table of
CFI check functions in loaded modules to reduce performance overhead.

If unsure, say Y.

depends
CONFIG_CFI_CLANG
CONFIG_MODULES