/usr/lib/x86_64-linux-gnu/libXext.so.6 is in libxext6 2:1.3.0-3build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libXext.so.6.4.0
/usr/lib/x86_64-linux-gnu/libXext.so.6.4.0