Problem identified

Joomla\CMS\Categories\Categories::getInstance() has been deprecated with 4.0 and will be removed with 6.0.

The suggested alternative is to use the ComponentInterface.

Factory::getApplication()->bootComponent($component)->getCategory($options, $section);

There is a difference though: getInstance() caches the category service instance. When you query Categories::getInstance($extension, $options)::get() twice for the same category, you'll get the same CategoryNode, without querying the database twice.

Joomla\CMS\Categories\CategoryServiceTrait::getCategory() creates a new categories service on each call and by that you'll not benefit from the nodes cache.

Proposed solution

Is it possible to add an instance cache to the Joomla\CMS\Categories\CategoryServiceTrait?

Open questions