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

SLOB (Simple Allocator)

modulename: slob.ko

configname: CONFIG_SLOB

Choose SLAB allocator
└─>SLOB (Simple Allocator)
In linux kernel since version 5.2 (release Date: 2019-07-07)  
SLOB replaces the stock allocator with a drastically simpler
allocator. SLOB is generally more space efficient but
does not perform as well on large systems.

source code:
depends
CONFIG_EXPERT
NOT CONFIG_PREEMPT_RT