Yes when this problem was first found both sites had the same extensions and versions. The development site was originally a clone of the site that is giving problems. Now the development site has additional components on trial.

The Cloudflare ordering difference is in Admin. I don't know what component is launching Cloudflare or how to change the order.

If possible exclude CloudFlare from the admin section.
It will cause issues.

I can't disable Cloudflare just in Admin.

The problem component appears to be administrator\components\com_k2\helpers\html.php where line 129 :

$document->addScript('cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js');

throws this error:

TypeError: this._addClass is not a function

This doesn't have to do with Cloudflare, it is just using Cloudflare's CDN. And it looks like a JS conflict.

Maybe you are using a modified template for the Joomla admin panel (I see in your screenshot it is not vanilla Joomla) that loads different JS files. Go to Extensions -> Templates and make sure you are using Isis.