Maybe you don't know that to install the Linux-zen on manjaro it is not possible through the mirrorlists of the distro (neither through Pacman nor through Yay). But it is possible to circumvent the problem with simple steps.
Why install zen kernel?
It a kernel tuned for performance, aimed at improving performance of
desktops at the cost of throughput and power usage. It is also sometimes
considered the best kernel for gaming. It has a low latency and
high-frequency scheduling. The kernel facilitates faster speeds and features a more optimized scheduler.