D:\tmp\pm>type unsafe_regex_BEGIN.pl
exit;

'' =~ ('(?{B'.'EGIN{die "owned"}})');


D:\tmp\pm>perl -c unsafe_regex_BEGIN.pl
Eval-group not allowed at runtime, use re 'eval' in regex m/(?{BEGIN{die "owned"
}})/ at unsafe_regex_BEGIN.pl line 3.

D:\tmp\pm>perl -v

This is perl 5, version 32, subversion 1 (v5.32.1) built for MSWin32-x64-multi-thread