I need Full Action Name in Ajax Controller magento 2.

    protected $request;
    public function __construct(
        ...
        \Magento\Framework\App\Request\Http $request
    ) {
        
        $this->request = $request;
    }
    
    $action = $this->request->getFullActionName();

This always giving me my ajax controller full action name.

I need ,suppose if i m on product page this should give me "catalog_product_view" .

If i m on search this should display "catalogsearch_result_index".

Please help.