Linebreaks disappear after an update of the post

hi/
my problem is that Linebreaks disappear after an update of the post.
When I edit a post and press Enter twice – I’m getting pretty good line breaks.
Click on Update and everything is fine.
When I edit the post again later – even if I did not do any changes and click Update all Linebreaks disappear …
Anyone know this problem?
the site is here:
https://174.137.187.89/~amnonba/projectpt1/%D7%A8%D7%97-%D7%92%D7%95%D7%A8%D7%93%D7%95%D7%9F-9-%D7%AA%D7%9C-%D7%90%D7%91%D7%99%D7%91-%D7%91%D7%99%D7%AA-%D7%96%D7%A8%D7%A1%D7%A7%D7%99/
Thank you