There is a reason for that - requires maintenance.
https://aur.archlinux.org/packages/opensnitch-ebpf-module#comment-965841
And
Further in a newer comment
https://aur.archlinux.org/packages/opensnitch-ebpf-module#comment-965976
DKMS is not an option here - this is an eBPF program and not a kernel module and hence this package does not use DKMS