How to check PLP page layered navigation attributes selected or not using Observer?

I am using event ( catalog_product_collection_load_before )for check PLP page layered navigation attributes selected or not, my observer,

appcodeZeroDescBlockObserverData.php

<?php

namespace ZeroDescBlockObserver;

use MagentoFrameworkEventObserverInterface;
use MagentoCatalogModelLayerResolver as LayerResolver;
use PsrLogLoggerInterface;

class Data implements ObserverInterface
{
    /**
     * @var MagentoCatalogModelLayerCategory
     */
    protected $catalogLayer;
    
    /**
     * @var PsrLogLoggerInterface
     */
    private $logger;

    /**
     * @param LayerResolver $layerResolver,
     */
    public function __construct(
        LayerResolver $layerResolver,
        LoggerInterface $logger
    ) {
        $this->catalogLayer = $layerResolver->get();
        $this->logger = $logger;
    }

    public function execute(MagentoFrameworkEventObserver $observer)
    {
        
        // Get selected filters
        $layer         = $this->catalogLayer;
        $activeFilters = $layer->getState()->getFilters();
        
        // checking variable activeFilters using log
        $writer = new ZendLogWriterStream(BP . '/var/log/custom.log');  
        $logger = new ZendLogLogger();  
        $logger->addWriter($writer);  
        $logger->info('Your log details: ' .$activeFilters); 

    }
}

Log not return anything.

Any help thanks?