I have seen the topics created related to a term called pipewire - and I have not paid attention to them - signed off as -
I don’t use it - I don’t even know what it is
But after a couple of pings from users (the broad team mention) I checked my system - a purely window manager and pulseaudio - no pulseeffects - and I have no pipewire packages.
After checking the ISO profiles - none of them has pipewire or pulseeffects as a part of the ISO.
pipewire is not mandatory 
The decision to use pipewire is a user decision - because the user has chosen to install pulseeffects - and pulseeffects 5.x has hard dependency on pipewire.
Manjaro pipewire FUD
All the comments on Manjaro making a change without being ready - is FUD - it is members throwing around statements with no hold in fact. So for those saying Manjaro changed to pipewire - please do your homework.
pulseaudio replaced with pipewire
This will happen if you have installed pulseeffects as part of your specific user setup.
Upstream pulseeffects has replaced pulseaudio with pipewire - and that has nothing to do with Manjaro but a design choice made by the developers of pulseeffects.
If you want pulseeffects but want no pipewire - for one reason or another - you can’t have pulseeffects in the latest pulseeffects package has a hard dependency on pipewire.
It will also happen on KDE because upstream KDE as decided to make pipewire a hard dependency of the kwin window manager.
Keep pulseaudio with pulseeffects
To keep pulseaudio with pulseeffects - you need resort to pulseeffects-legacy package if you require the content of pulseeffects.
Summary
pipewire is a hard dependency on latest pulseeffects 5.x so if want to update the pulseeffects packge then you will get pipewire - otherwise not.
You can also replace pulseaudio with pipewire - again this is a user decision.
Manjaro ISO - in their present state - does not install pipewire nor pulseeffects.
I stand corrected by @pixel - thank you.