/usr/lib/puredata/extra/fexpr~.pd_linux is in puredata-extra 0.46.7-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/puredata/extra/expr~/fexpr~.pd_linux
/usr/lib/puredata/extra/expr~/fexpr~.pd_linux