Maybe I'm lucky and getting A/B'ed.
The big white space is a <div> with a script with "adsbygoogle".
Code:
<div style='text-align:center; height: 90px; margin:2px auto 16px;'>
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
Logged out & in, no difference.