Drupal 10: Menu items do nothing on click or hover

Problem/Motivation

I recently raised a connected issue concerning the use of the 'spaceless' tag in the seeds-toolbar.html.twig template and I have temporrily fixed that locally and got it running but now I am seeing something else...

Development environment

Drupal Version: 10.0.0-beta2
Web Server: Apache/2.4.33 (Win64) OpenSSL/1.0.2u mod_fcgid/2.3.9
Database: MySQL  5.7.24
PHP: 8.1.0
Front end theme  - a custom subtheme Bootstrap5 (2.02)

Symptoms

Clicking the burger icon in the Seeds toolbar does not open the Admin menu...

...and I am seeing numerous JS errors in the console which seem to relate 'once' not being a function? ...

GET https://drupal10/core/themes/claro/images/menu-expanded.png 404 (Not Found)
drupal.js?v=10.0.0-beta2:64 Uncaught TypeError: $(...).once is not a function
    at Object.attach (seeds-toolbar.back.js?rl0x0u:26:52)
    at drupal.js?v=10.0.0-beta2:166:24
    at Array.forEach (<anonymous>)
    at Drupal.attachBehaviors (drupal.js?v=10.0.0-beta2:162:34)
    at drupal.init.js?v=10.0.0-beta2:32:12
    at HTMLDocument.listener (drupal.init.js?v=10.0.0-beta2:20:7)
attach @ seeds-toolbar.back.js?rl0x0u:26
(anonymous) @ drupal.js?v=10.0.0-beta2:166
Drupal.attachBehaviors @ drupal.js?v=10.0.0-beta2:162
(anonymous) @ drupal.init.js?v=10.0.0-beta2:32
listener @ drupal.init.js?v=10.0.0-beta2:20
setTimeout (async)
Drupal.throwError @ drupal.js?v=10.0.0-beta2:63
(anonymous) @ drupal.js?v=10.0.0-beta2:168
Drupal.attachBehaviors @ drupal.js?v=10.0.0-beta2:162
(anonymous) @ drupal.init.js?v=10.0.0-beta2:32
listener @ drupal.init.js?v=10.0.0-beta2:20
drupal.js?v=10.0.0-beta2:64 Uncaught TypeError: $(...).once is not a function
    at Object.attach (seeds-toolbar.js?rl0x0u:156:12)
    at drupal.js?v=10.0.0-beta2:166:24
    at Array.forEach (<anonymous>)
    at Drupal.attachBehaviors (drupal.js?v=10.0.0-beta2:162:34)
    at drupal.init.js?v=10.0.0-beta2:32:12
    at HTMLDocument.listener (drupal.init.js?v=10.0.0-beta2:20:7)
attach @ seeds-toolbar.js?rl0x0u:156
(anonymous) @ drupal.js?v=10.0.0-beta2:166
Drupal.attachBehaviors @ drupal.js?v=10.0.0-beta2:162
(anonymous) @ drupal.init.js?v=10.0.0-beta2:32
listener @ drupal.init.js?v=10.0.0-beta2:20
setTimeout (async)
Drupal.throwError @ drupal.js?v=10.0.0-beta2:63
(anonymous) @ drupal.js?v=10.0.0-beta2:168
Drupal.attachBehaviors @ drupal.js?v=10.0.0-beta2:162
(anonymous) @ drupal.init.js?v=10.0.0-beta2:32
listener @ drupal.init.js?v=10.0.0-beta2:20
drupal.js?v=10.0.0-beta2:64 Uncaught TypeError: $(...).once is not a function
    at Object.attach (seeds-toolbar.js?rl0x0u:266:10)
    at drupal.js?v=10.0.0-beta2:166:24
    at Array.forEach (<anonymous>)
    at Drupal.attachBehaviors (drupal.js?v=10.0.0-beta2:162:34)
    at drupal.init.js?v=10.0.0-beta2:32:12
    at HTMLDocument.listener (drupal.init.js?v=10.0.0-beta2:20:7)