Here are some of the issues with the markdown provided in the linked question:
The use of the HTML
<img> tag is incorrect. The correct usage would be
Markdown for code blocks used to be an indent of 4 spaces. However, this has been updated to allow for a triple backtick that would initiate the code block, and a closing triple backtick to finish the code block. Based on the examples in the markdown/editing help, these triple backtick sequences need to be on their own line. Sure, in some cases they can be mixed in with the code, but proper identification of the code block (and just because you're showing that your coding style is nicely structured) requires the opening/closing triple backtick sequence to be on their own lines. So, the correct usage would be
<your code here>
```<your code here>
<some more code>```
The main issue with the post during your revision was the last triple backtick on the same line of code, which caused issues with the markdown image notation
[![description]]. When the post was post was updated to use the regular 4-space indentation as code block markdown, the backticks were removed the problem didn't show anymore.
I've updated the code in that question to reflect the correct use of markdown (by removing the
<img> tagging; SE only supports a subset of HTML tags anyway).
Here's a mockup situation similar to the original question: