DATA is the handle used by Perl to read the source file. As a result, use utf8; affects not just the source file, but DATA as well. Specifically, it adds a :utf8 layer to DATA. Since DATA already has a :utf8 layer, so adding :encoding(UTF-8) is incorrect (though harmless).

Furthermore, use open ':std', ':encoding(UTF-8)'; adds :encoding(UTF-8) to not just STDOUT, but also to STDIN and STDERR. (It also causes instances of open in scope to add that layer by default.) And it does so a compile-time. This is usually the better route. 

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
use utf8;
use open ':std', ':encoding(UTF-8)';

say substr('Ĉon Flux', 0, 1);
say substr <DATA>, 0, 1;

__DATA__
Ĉon Flux

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In reply to Re^2: Special character not being captured by ikegami
in thread Special character not being captured by Lady_Aleena

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