Hi @Dnd-Mafer. Thank you for your report.
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Here is the patch for Magento Open Source

diff --git a/vendor/magento/module-catalog/Model/ResourceModel/Category/Collection.php b/vendor/magento/module-catalog/Model/ResourceModel/Category/Collection.php
--- a/vendor/magento/module-catalog/Model/ResourceModel/Category/Collection.php
+++ b/vendor/magento/module-catalog/Model/ResourceModel/Category/Collection.php	(date 1744890081397)
@@ -375,19 +375,21 @@
         array $categoryIds,
         int $websiteId
     ) : array {
-        $subSelect = clone $this->_conn->select();
-        $subSelect->from(['ce2' => $this->getTable('catalog_category_entity')], 'ce2.entity_id')
-            ->where("ce2.path LIKE CONCAT(ce.path, '/%') OR ce2.path = ce.path");
-
         $select = clone $this->_conn->select();
         $select->from(
             ['ce' => $this->getTable('catalog_category_entity')],
             'ce.entity_id'
         );
-        $joinCondition =  new \Zend_Db_Expr("cp.category_id IN ({$subSelect})");
+
+        $select->joinLeft(
+            ['ce2' =>  $this->getTable('catalog_category_entity')],
+            new \Zend_Db_Expr("ce2.path LIKE CONCAT(ce.path, '/%') OR ce2.path = ce.path"),
+            []
+        );
+
         $select->joinLeft(
             ['cp' => $this->getProductTable()],
-            $joinCondition,
+            'cp.category_id = ce2.entity_id',
             'COUNT(DISTINCT cp.product_id) AS product_count'
         );
         if ($websiteId) {

Hi @engcom-Bravo. Thank you for working on this issue.
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Hi @Dnd-Mafer,

Thanks for your reporting and collaboration.

We have tried to reproduce the issue in Latest 2.4-develop instance with 100k products and 2000 categories with 7 root categories and we are not able to reproduce the issue.Kindly refer the attached video.

Category page appears quickly.Could you please let us know still if we are missing anything.

Thanks.