/usr/share/doc/libgbm1/changelog.Debian.gz is in libgbm1 10.1.0-4ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgbm1/../libgl1-mesa-dri/changelog.Debian.gz
/usr/share/doc/libgbm1/../libgl1-mesa-dri/changelog.Debian.gz