Site issues with landing pages

Description

Hello everyone! :)
We are in urgent need of someone that could help us understand an issue we are facing with our landing pages that display in the SERP as they look broken for some reason so will do my best to explain everything here:
The issue seems to be related to our posts that are connected with the main pages,
When we Google "Jackpot Casinos FatGambler" as an example we get this displayed in the SERP as you can see in the screenshot attached.
However, when clicking on the top URL:
https://fatgambler.ca/jackpot-casinos/
The page looks perfect and user friendly.
But when we click on the URL below:
https://fatgambler.ca/jackpot-casino/top-jackpot-slots/
The page looks very broken and the user can't scroll up the page. It seems like these type of posts/ pages are locked to our Table of Contents section that we have in place for our site as you can see in the other screenshot attached since it's the only part of the page that is visible for the user.
Not sure if this is a Dev or SEO issue, so if someone please could help us with a solution to this problem would be much appreciated.
Kindly send us a brief explanation of what the issue could be related to and your quote to get this fixed - Thank you very much, looking forward to hear from you!