I suspect you have a quote in the value of $File::Find::name. The following could be used to generate the shell literal (instead of "'$File::Find::$name'"):

sub to_sh_literal {
   my ($s) = @_;
   # Assuming bourne shell.
   $s =~ s/'/'\\''/g;
   $s = "'$s'";
   return $s;
}
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But why are you using grep (the external tool) at all?

Update: Removed encode since file names are bytes, not text.