Custom Code is Affecting an Index Page

My website has an index page, but clicking an image doesn't open up the connected sub-page. I'm on Version 7.0, Montauk family (Montauk template). There's custom code that's affecting the ability of the index's sub-pages to open. I took over this website from a predecessor, but I don't know code. 

In the "Website Tools" section of my website, I'm seeing the following: 

Header

<!-- Google Tag Manager -->
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-WFQ4PR9');</script>
<!-- End Google Tag Manager -->

Would someone be able to tell me what this code is doing? 

From,

Eric

@Eric_Playing_on_Air Hi! The code you shared is related to Google Tag Manager and doesn't prevent the image links from opening pages. 

@Eric_Playing_on_Air Is there a Custom Google Search Engine on your website? 

@Lesum Hi Sam,

Yes, there is a Custom Google Search Engine on our homepage. Could that be interacting with my problem somehow?

Best,

Eric

Okay, interesting. I'll try taking it out and seeing if that solves the problem. 

@Eric_Playing_on_Air If you have access to your Google Custom Search Engine account, you might want to check if you can change some settings like disabling Results Browsing History. Hopefully, you can fix it soon.

Good news, the issue has been fixed. Taking out the Custom Google Search Engine resolved the issue.