Problem with register_setting()

Your code looks fine at first glance, but the Plugin Checker is complaining about the dynamic argument in register_setting(). This usually happens when register_setting() receives an argument that is not a direct function reference or a string literal.

function inseco_sanitize_textarea($input) {
    return wp_kses_post($input);
}

register_setting(
    'inseco_settings_group',
    'inseco_code_after_page',
    array(
        'type'              => 'string',
        'sanitize_callback' => 'inseco_sanitize_textarea', // Ensure function exists before this call
    )
);