I think I found a bug in saving a post.
If I try to insert the string you see in the screen, and try to save, I encounter error 500.
Lately I’ve been experiencing another problem in saving posts.
After saving I try to close the page, but keep telling me to save before leaving. If I close the page and open the post online, the changes are all correct, but if I return to the edit of the post, the last line is always cut.