/usr/lib/x86_64-linux-gnu/plplot5.10.0/driversd/null.driver_info is in libplplot12 5.10.0+dfsg2-0.4+b2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
null:Null device:-1:null:42:null