Hi.
Here is a part of source code:
<meta name="robots" content="index, follow, max-snippet:-1, max-video-preview:-1, max-image-preview:large"/>
<link rel="canonical" href="https://mydomain.com/" />
<meta property="og:locale" content="en_GB">
<meta property="og:type" content="website">
<meta property="og:url" content="https://mydomain.com/">
<meta property="og:updated_time" content="2020-03-11T10:11:26+02:00">
<link rel='dns-prefetch' href='//cdnjs.cloudflare.com' />
<link rel='dns-prefetch' href='//www.youtube.com' />
<link rel='dns-prefetch' href='//s.w.org' />
<link rel='dns-prefetch' href='//youtube.com' />
<link rel="alternate" type="application/rss+xml" title="xxxxxxxxxxxxxxxxxxx » Feed" href="https://mydomain.com/feed/" />
<link rel="alternate" type="application/rss+xml" title="xxxxxxxxxxxxxxxxxxx » Comments Feed" href="https://mydomain.com/comments/feed/" />
<link data-asynced="1" as="style" onload="this.onload=null;this.rel='stylesheet'" data-optimized="1" rel='preload' id='qodeblock-fontawesome-css' href='https://mydomain.com/wp-content/litespeed/cssjs/6793b.css' type='text/css' media='all' />
<noscript>
<link data-optimized="1" rel='stylesheet' id='qodeblock-fontawesome-css' href='https://mydomain.com/wp-content/litespeed/cssjs/6793b.css' type='text/css' media='all' />
</noscript>
<link data-asynced="1" as="style" onload="this.onload=null;this.rel='stylesheet'" data-optimized="1" rel='preload' id='wp-block-library-css' href='https://mydomain.com/wp-content/litespeed/cssjs/922ce.css' type='text/css' media='all' />
<noscript>
<link data-optimized="1" rel='stylesheet' id='wp-block-library-css' href='https://mydomain.com/wp-content/litespeed/cssjs/922ce.css' type='text/css' media='all' />
</noscript>
<link data-asynced="1" as="style" onload="this.onload=null;this.rel='stylesheet'" data-optimized="1" rel='preload' id='qodeblock-style-css-css' href='https://mydomain.com/wp-content/litespeed/cssjs/d23fb.css' type='text/css' media='all' />
<noscript>
<link data-optimized="1" rel='stylesheet' id='qodeblock-style-css-css' href='https://mydomain.com/wp-content/litespeed/cssjs/d23fb.css' type='text/css' media='all' />
</noscript>
You can see that all files from //mydomain.com/wp-content/litespeed/cssjs/ are loaded with HTTP not https.