Magento – Magento 2 breadcrumbs issue on product view page

I did the extension in below GitHub Url with below feature :

https://github.com/vijays91/Magento-Advanced-Breadcrumbs

• Display the full path in product breadcrumbs (show all category paths).
• To display the single and multiple category breadcrumbs in product view page.
• Helps this module, search engines to parse your breadcrumbs (Home / Search result for: 'XXX' / XXX).
• Breadcrumbs are added to customer account pages.
• Added breadcrumbs to contact us page.

NO, the full page cache is not the culprit.

DON'T DISABLE FULL PAGE CACHE.

The logic flow is clearly described in \Magento\Catalog\Helper\Data::getBreadcrumbPath() when it runs $category = $this->getCategory().

Just see the getCategory() code

/**
 * Return current category object
 *
 * @return \Magento\Catalog\Model\Category|null
 */
public function getCategory()
{
    return $this->_coreRegistry->registry('current_category');
}

It returns an object saved in the registry called current_category. If the object is not present, the breadcrumbs will be empty.

For example, if you make a first time access (clean browser and magento cache) to a product directly from search box, you will have that breadcrumbs will be empty because registry('current_category') was not setted.

Otherwise, if you make a first time access (clean browser and magento cache) to a product after visited its category, breadcrumbs will be present, because registry('current_category') was setted.

Then, every time you make a second visit to same product page you just see the same result, because FPC (FULL PAGE CACHE) JUST CACHE EVERY GET REQUEST AND RESPONSE WITH THE CONTENT OF THE FIRST TIME VISIT.