Why we can’t install debug symbols (e.g debug symbols for Plasma/KDE apps) on Manjaro ? while it’s possible on Ubuntu based distributions ?
Debian based Distributions enable debug symbols at compile time of applications.
Arch based Distributions don’t do that. The reason is, that enabling debugging symbols slows down applications. It can debated if this is still a reason, because CPU are usually quite fast and the impact of debugging symbols is not that big. But it also makes packages bigger or there would be the need of spilt packages, which is not liked by Arch maintainer.
You can recompile a package with debug symbols enabled. Keep in mind that you might need to recompile some libraries too.