CPU vulnerability mitigations would typically be distributed with the intel-microcode package for Intel processors on Debian-based distributions, for example.

And QubesOS isnt based on linux kernel. It uses Xen. Linux is used in the Qubes aka VMs.

The dom0 is very much running a Linux kernel, the same way your domU:s are typically running Linux kernels (although you could probably run any kernel in hvm mode).

As an example, here is the documentation on how to manage updates for the dom0 kernel:

https://www.qubes-os.org/doc/how-to-install-software-in-dom0/#kernel-upgrade

They went crying about WPEngine having found a good business model around Wordpress support, and started sabotaging for them.

https://www.theverge.com/2024/10/2/24260158/automattic-demand-wp-engine-revenue-wordpress-battle

Looks like they lost in court a few days ago!

https://www.theverge.com/2024/12/10/24318350/automattic-restore-wp-engine-access-wordpress