/usr/lib/x86_64-linux-gnu/libX11-xcb.so is in libx11-xcb-dev 2:1.6.2-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1.0.0
/usr/lib/x86_64-linux-gnu/libX11-xcb.so.1.0.0