Magento 2 Custom adminhtml validation rules doesn’t work

Custom adminhtml validation rules from Magento 2 docs on purely installed Magento 2.4.3 and Magento 2.4.2 doesn’t work.

Vendor/Module/view/frontend/requirejs-config.js

var config = {
  config: {
    mixins: {
      'mage/validation': {
        'Vendor_Module/js/validation-mixin': true
      }
    }
  }
}

Vendor/Module/view/frontend/web/js/validation-mixin.js

define(['jquery'], function($) {
  'use strict';

  return function() {
    $.validator.addMethod(
      'validate-five-words',
      function(value, element) {
        return value.split(' ').length == 5;
      },
      $.mage.__('Please enter exactly five words')
    )
  }
});

Vendor/Module/etc/adminhtml/system.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
    <system>
        <tab id="vendor" class="vendor-tab" translate="label">
            <label>Vendor</label>
        </tab>

        <section id="vendor" translate="label" showInDefault="1" showInWebsite="1" showInStore="1">
            <label>Label</label>
            <tab>Vendor</tab>
            <resource>Vendor_Module::config</resource>

            <group id="module" showInDefault="1" showInWebsite="1" showInStore="1" translate="label">
                <label>Module</label>

                <field id="field" showInDefault="1" showInWebsite="1" showInStore="1" translate="label" canRestore="1" type="text">
                    <label>Field</label>
                    <validate>validation-mixin</validate>
                </field>
            </group>
        </section>
    </system>
</config>

Vendor/Module/etc/config.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <vendor>
            <module>
                <field>1 2 3 4 5</field>
            </module>
        </vendor>
    </default>
</config>

When saving, nothing happens to me.

When adding standard Magento rules <validate>validate-number</validate>, they work.

What am I doing wrong? or maybe something is missing?