By default, Squirrly SEO loads the frontend.min.css style for Squirrly SEO Blogging Assistant. This way the Twitter block, Wikipedia blocks, and Articles block you import using Squirrly SEO it will keep the same style as in the editor.
The Squirrly SEO META looks like this in the source-code:
<link rel='stylesheet' href='https://howto.squirrly.co/modules/882eb7ffb0/view/assets/css/frontend.min.css' type='text/css' media='all' />
If you are not using Squirrly SEO Blogging Assistant to insert Twitter blocks, Wikipedia blocks or Article blocks into your content you can prevent it from loading in frontend.
Remove Squirrly frontend.min.css from frontend
Open the wp-config.php file in File Manager and add this line after the WP_DEBUG line:
This way Squirrly will know to not to load the css link tag anymore in header.