default or selected kernelversion does not have config value CONFIG_ENABLE_MUST_CHECK.
Result is shown for kernelversion 6.8.2

Enable __must_check logic


Linux Kernel Configuration
└─>Kernel hacking
└─>Compile-time checks and compiler options
└─>Enable __must_check logic
In linux kernel since version 2.6.19 (release Date: 2006-11-29)  
Enable the __must_check logic in the kernel build. Disable this to
suppress the "warning: ignoring return value of 'foo', declared with
attribute warn_unused_result" messages.