Target_blank and embed video disappear

Hi All!

I have a problem for a while now
Every time I create a page/post and put links that will open in a new tab (target_blank) after a while, wordpress eliminates or erases the open in new tab (target_blank)

In addition, when I have embedded a youtube video in my pages/posts, the disappears after some time from the page, in there is no any trace why it erased from the wordpress editor.

Need help about it

Thanks in advance

Tom