Why visible if added via Razor?

Question

HTML

Good afternoon!
There is a part in the block that should be filled either with a "description" or remain empty, but not disappear (so that the size of the block does not change. To do this, if the "description" is missing, I insert the code through Razor.  
But in this case, it is visible in the browser and not empty space.If
I paste directly into html, then everything is ok.In
html, everything is the
same.Why is this happening?
Is there any established practice for such tasks?