Classmates. Why can't I post a link to a website in a post?

Question

Classmates

Good afternoon!
If you insert a link to the site https://mkset.ru/ in your feed in OK, you will see the message "Links of this type are not supported" instead of the page preview. The rest of the social networks correctly form the page preview
https://monosnap.com/file/19MGw9g4O486CkduDEMXDUCY...
What does the OK robot not like? How to define it?
Tell me please.

Answer 1

just a guess.
In the robots.txt file, write down the selected primary spelling.
User-Agent: *
Host: mkset.ru
In the .htaccess file, write a 301 redirect from the non-main spelling to the main one.
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www.mkset.ru
RewriteRule ^(.*)$ mkset.ru/$1 [R=301,L]