Saving theme creates unnecessary patterns

I encountered this problem working with the plugin version 2.0.2 and WooCommerce templates, but it may be more widespread.

What happens?

Originally, the taxonomy-product_cat.html template contains this snippet:

<!-- wp:query-no-results -->
<!-- wp:pattern {"slug":"woocommerce/no-products-found"} /-->
<!-- /wp:query-no-results -->

In the editor the pattern is visible as a paragraph block telling "No products were found matching your selection."

When I modify the template and save the theme to files, the whole template gets replaced with:

<!-- wp:pattern {"slug":"mytheme/taxonomy-product_cat"} /-->

and a new pattern is created in patterns/taxonomy-product_cat.php

This pattern contains:

<!-- wp:query-no-results -->
<!-- wp:paragraph -->
<p><?php echo __('No products were found matching your selection.', 'mytheme');?></p>
<!-- /wp:paragraph -->
<!-- /wp:query-no-results -->

I also tried with a custom pattern:

/**
 * Title: no-products-found
 * Slug: mytheme/no-products-found
 * Categories: hidden
 * Inserter: no
 */
?>
<!-- wp:paragraph -->
<p><?php echo __('No products were found matching your selection.', 'mytheme');?></p>
<!-- /wp:paragraph -->

and it behaves the same as the WooCommerce one.

What should happen?

As I already have <!-- wp:pattern {"slug":"woocommerce/no-products-found"} /--> (or my custom pattern) which is dynamically translated, I want to keep it in a regular template taxonomy-product_cat.html after saving without getting that mostly redundant taxonomy-product_cat.php created.

May be related to

#533 Export creates new patterns by copying content from other patterns, without re-using them

Start by tracing the save-theme-to-files export path in the create-block-theme plugin and compare how taxonomy-product_cat.html handles the wp:pattern reference. Done means saving preserves the existing pattern reference in the template and does not create the redundant patterns/taxonomy-product_cat.php file; issue #533 may provide related context.