/usr/lib/x86_64-linux-gnu/libOSMesa.so is in libosmesa6-dev 10.1.0-4ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libOSMesa.so.6.5.3
/usr/lib/x86_64-linux-gnu/libOSMesa.so.6.5.3