Sumarry
I wanted to make my Konsole to let me clear scrollback while I am using screen so I googled how to do that.
Answer
~/.screenrc
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defscrollback 50000
# Press "Ctrl + a", "/" and then "Enter" to clear scrollback
# - Konsole disables the functionality if it is on subshell (= screen)
bind / eval "clear" "scrollback 0" "scrollback 50000"