[arch-general] nvidia-dkms pkgrel increase after every linux upgrade

I have recently installed nvidia-dkms as I use linux-hardened, although I have installed linux package as well, but I always boot to linux-hardened. Anyway I've noticed that nvidia-dkms increases pkgrel everytime linux package gets upgraded, why is that so? Taken from NVIDIA wiki: Custom kernel If you are using a custom kernel, compilation of the Nvidia kernel modules can be automated with DKMS. Install the nvidia-dkms package (or a specific branch). The Nvidia module will be rebuilt after every Nvidia or kernel update thanks to the DKMS pacman hook. Correct me if I'm wrong but it doesn't mean that nvidia module will be rebuilt after kernel update thanks to the DKMS pacman hook? So why should nvidia-dkms upgrades?