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

BPF based packet filtering framework (BPFILTER)

modulename: sockopt.ko

configname: CONFIG_BPFILTER

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>BPF based packet filtering framework (BPFILTER)
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This builds experimental bpfilter framework that is aiming to
provide netfilter compatible functionality via BPF

source code:
net/ipv4/bpfilter/sockopt.c
selects
CONFIG_USERMODE_DRIVER

depends
CONFIG_BPF
CONFIG_INET
CONFIG_NET