Store Speed issue with Reindex. Magento 2

I have a Magento2.3.5 Version but that store is causing a strange issue Store is really fast when just Reindex is runned but after 2 or maybe 3 hrs it became really slow and I have to run Reindex again. So to Trace that issue I’ve checked System.log file which was showing
[2024-06-28 11:12:46] main.CRITICAL: Item (MagentoCatalogModelProductInterceptor) with the same ID "881" already exists. [] []
so for that I’ve created a plugin which code is

di.xml

<?xml version="1.0"?>
 
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
 <type name="MagentoEavModelEntityCollectionAbstractCollection">
    <plugin name="find_duplicate_entry" type="TreezeeDuplicateEntrypluginCollection" sortOrder="20"/>
 </type>
</config>

while the plugin code is

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 */
namespace TreezeeDuplicateEntryplugin;
use MagentoFrameworkDataCollectionEntityFactoryInterface;
use MagentoFrameworkOptionArrayInterface;
 
class Collection
{
    /**
     * @param MagentoEavModelEntityCollectionAbstractCollection $subject
     * @param Closure $process
     * @param MagentoFrameworkDataObject $dataObject
     * @return $this
     */
    public function aroundAddItem(MagentoEavModelEntityCollectionAbstractCollection $subject, Closure $process, MagentoFrameworkDataObject $dataObject)
    {
        try{
            return $process($dataObject);
        }catch ( Exception $e){
            return $this;
        }
    }
}

now this code fixes the above issue but still the Store Reindex issue was there so now when I looked at the System.log file the it shows

Now I dont know why this issue is happening or it is related to speed issue or not and how to fix that.. any help would be really appreciated Thanks.