functions.php

<?php


add_filter( 'tribe_get_list_widget_events', 'cc_tribe_get_list_widget_events' );
function cc_tribe_get_list_widget_events( $posts ) {
	$output_posts = [];
	$used_posts = [];
	$query = new WP_Query([
		'eventDisplay'   => 'list',
		'posts_per_page' => 3,
		'tribe_render_context' => 'widget',
		'meta_query' => [
			'featured' => [
				'key' => 'featured',
				'value' => 'yes',
			],
	  ],
	]);
	foreach( $query->posts as $post ) {
		$output_posts[] = $post;
		$used_posts[] = $post->ID;
	}
	
	if ( count( $output_posts ) < 3 ) {
		$query = new WP_Query([
			'eventDisplay'   => 'list',
			'posts_per_page' => 3,
			'tribe_render_context' => 'widget',
			'post__not_in' => $used_posts,
			'meta_query' => [
				'linked' => [
					'key' => 'link_url',
					'compare' => '!=',
					'value' => '',
				],
			],
		]);
		foreach( $query->posts as $post ) {
			if ( count( $output_posts ) >= 3 ) {
				break;
			}
			$output_posts[] = $post;
			$used_posts[] = $post;
		}
	}


	if ( count( $output_posts ) < 3 ) {
		$query = new WP_Query([
			'eventDisplay'   => 'list',
			'posts_per_page' => 3,
			'tribe_render_context' => 'widget',
			'post__not_in' => $used_posts,
		]);
		foreach( $query->posts as $post ) {
			if ( count( $output_posts ) >= 3 ) {
				break;
			}
			$output_posts[] = $post;
			$used_posts[] = $post;
		}
	}
	return $output_posts;
}