/usr/lib/x86_64-linux-gnu/libksignalplotter.so is in libkf5sysguard-dev 4:5.12.4-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libksignalplotter.so.7
/usr/lib/x86_64-linux-gnu/libksignalplotter.so.7