get_the_ID（）的奇怪问题

I have a little PHP script that uses get_the_ID() and then scrubs it to create a button that points to a category page on a WP site. The issue is that after a couple months of this working fine, a mysterious colon has showed up. I can seem to find in WP documentation what has changes and why this colon is now being printed to the page.

The code generating this is as follows:

<?php 
        $simpleCats= tribe_get_event_categories(
            get_the_ID(), array(
                'before'       => '',
                'sep'          => '',
                'after'        => '',
                'label'        => '', 
                'label_before' => '',
                'label_after'  => '',
                'wrap_before'  => '<div class="avia-button-wrap avia-button-left eventCatBtn">',
                'wrap_after'   => '</div>'
            )
        );
        $simpleCats= preg_replace("/events\/category\//", "", $simpleCats);
        echo $simpleCats;
    ?>

Any ideas why this colon is being printed?