It’s because the forum will use any html tags you type. It’s making a new paragraph because you’ve written an opening <p> element tag. In future use the code formatting button when typing any html code into the forum.
When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (').