I’m using pipewire with easyeffects and they both work great.
For pipewire I’ve installed all the available compatibility layers: pipewire-pulse, pipewire-alsa, pipewire-jack, as well as every lib32 variant. Without all of these some apps would not work via pipewire.
As for easyeffects, depending on your distro and how you install it, you might need to install the plugins separately. Otherwise the app will open but it won’t be able to actually apply any effects. First time I tried to use it I was confused about this.
This wouldn’t appear like this when upgrading the system with pacman. pacman does not automatically remove orphaned dependencies during upgrades. You have to query for them and remove them explicitly as a separate operation afterwards. So in the OP what we’re seeing is the new versions of packages themselves getting smaller.