Why does layout slide out when rendering a page in a WordPress plugin?

Question

Twig

I am writing a plugin for WordPress, when working out the render method, I specify the file to be connected . Inside the render function, the data is transferred to the Twig template engine
<?php echo $this->render('index.php', []);?>

<?php return $this->_renderer->render($file,$params) ?>

An example index.php file

<div class="wrap">
    <p>Test</p>
    <p>Test</p>
</div>

But, I get the output.

I also tried to directly display the page (without TWIG), but the result is still the same.
After googling, I found results that relate to topics, basically. People write that the problem may be the absence of a closing tag somewhere in the template.
Perhaps I do not quite understand how to display the page correctly. But, how many articles I have not watched (
https://codex.wordpress.org/Writing_a_Plugin#Exter...
www.sitepoint.com/wordpress-plugin-development/,
https://premium.wpmudev.org/blog/wordpress -plugin-... www.hongkiat.com/blog/beginners-guide-to-wordpress...
etc.)
all show that you can just echo and you're done. Where is the catch?

Answer 1

inspect the page, it's worth looking at what the html gives there, it may also be possible to find the reason there