/usr/lib/pd/extra/earplug~/LICENSE.txt is in pd-earplug 0.2-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/pd/extra/earplug~/../../../../share/common-licenses/GPL-2
/usr/lib/pd/extra/earplug~/../../../../share/common-licenses/GPL-2