Why Facebook not picking correct image when sharing link ?

Some properties can have extra metadata attached to them. These are specified in the same way as other metadata with property and content, but the property will have extra :

You must add "og:image:secure_url" if the webpage requires HTTPS.

• og:image:url - Identical to og:image.
• og:image:secure_url - An alternate url to use if the webpage requires HTTPS.
• og:image:type - A MIME type for this image.
• og:image:width - The number of pixels wide.
• og:image:height - The number of pixels high.

A full image example:

<meta property="og:image" content="https://www.techqura.com/images/logo-1.png" />
<meta property="og:image:secure_url" content="https://www.techqura.com/images/logo-1.png" /> 
<meta property="og:image:type" content="image/png" /> 
<meta property="og:image:width" content="400" /> 
<meta property="og:image:height" content="300" />

So you need to add og:image property for HTTP URLs and og:image:secure_url for HTTPS

Note: Don't forget to refresh your link after updating your codes using - Facebook Debugger