/usr/share/doc/libkwin4-effect-builtins1/changelog.Debian.gz is in libkwin4-effect-builtins1 4:5.5.5-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libkwin4-effect-builtins1/../libkwineffects7/changelog.Debian.gz