I compared an archived copy of the comments page to the version today and noticed the HTML changed:
Old:
<tr>[...header...]</tr>
<tr id="pagespace" title="Y Combinator" style="height:10px"></tr>
<tr>[...comments...]</tr>
New: <tr>[...header...]</tr>
<tr><td style="height:10px"></td></tr>
<tr>[...comments...]</tr>
If you use Inspect Element to revert the change, it'll look as expected. You can test by resizing the browser window to mobile size, or by using your browser's mobile simulator.For some reason, this new method of adding space only works on desktop, while the old one worked on mobile as well.