Let's say I installed mumble server. At the time of installation, it showed X MB of storage will be used (can't remember).
If I uninstall those programs, the size is relatively less than that of installation size.
Why is that so? Do I need to remove its configuration? How can I find app-specific configuration?
It is normal. This happens because of dependencies.
If you run
sudo apt-get autoremove
orsudo apt-get autoremove --purge
(to remove all configs), you then get expected size.Next time please read about APT internals first by using docs like
or whole https://debian-handbook.info/download/stable/debian-handbook.pdf .