Yeah, it only becomes an issue if you're loading two classes that consume MooX::Role::CliOptions, and they each want different settings for the environment variable. None of your tests do that.

use 5.006;
use strict;
use warnings;
use Test::More;

{
    package My::Class1;
    use Moo;
    $ENV{MRC_NO_STDOPTS} = 1;  # do NOT want 'debug' and 'verbose'
    with 'MooX::Role::CliOptions';
}

{
    package My::Class2;
    use Moo;
    $ENV{MRC_NO_STDOPTS} = 0;  # do want 'debug' and 'verbose'
    with 'MooX::Role::CliOptions';
}

ok( ! My::Class1->new->can('verbose') );
ok(   My::Class2->new->can('verbose') );

done_testing;
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