/usr/lib/gwyddion/plugins/ is in gwyddion-plugins 2.44-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/gwyddion/plugins/file/
/usr/lib/gwyddion/plugins/file/dump
/usr/lib/gwyddion/plugins/process/
/usr/lib/gwyddion/plugins/process/invert_narray.rb
/usr/lib/gwyddion/plugins/process/invert_perl.pl
/usr/lib/gwyddion/plugins/process/invert_perl.pl.rgi
/usr/lib/gwyddion/plugins/process/invert_python.py
/usr/lib/gwyddion/plugins/process/invert_python.py.rgi
/usr/lib/gwyddion/plugins/process/invert_ruby.rb
/usr/lib/gwyddion/plugins/process/invert_ruby.rb.rgi
/usr/lib/gwyddion/plugins/process/yellow.sh
/usr/lib/gwyddion/plugins/process/yellow.sh.rgi