unlimited_wp_tags.php

<?php
/*
Plugin Name: Unlimited WordPress Tags!
Description: Enables the default of unlimited tags in the tag cloud to actually be unlimited (docs say unlimited, code says 45 - this fixes that.)
Version: 0.1
Author: Ryan Oeltjenbruns
Author URI: https://rohjay.one
License: GPLv2 or later
Text Domain: Tags, Tag cloud, Unlimited tags, Woohoo!
*/

add_filter( 'widget_tag_cloud_args', function($args) {
    $args['number'] = 0;
    return $args;
});