You are breaking perl by doing the vorboten:
From perldoc perlsyn:

If any part of LIST is an array, foreach will get very confused if you add or remove elements within the loop body, for example with splice. So don't do that.

The shift within the for loop is doing just that.

Here is an alternate version of the sub that behaves the way I think you intend, which does not use the shift:

sub article_title1 {
   local $_ = shift(@text); # left in for side effect
   my $BlankSeen=0;
   for (@text){
      $BlankSeen ?
           print "# TEXT-2 = '$_'\n"
         :
           print "# TEXT-1 = '$_'\n";
      $BlankSeen = 1 if  (/^$/);
   }
}
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