Hey there,
Normally, how our EasyBlog render mobile responsive works is when the system detected user view webpage in mobile/tablet, it will automatically inject this class name 'is-mobile' into the Easyblog HTML div wrapper, so that it can render properly in mobile view.
The reason this happens is because when there is first person access
https://www.linuxsecrets.com/ in desktop view, the Joomla cache system will cache the html data.
So when the next person access your site in mobile view, it will load the cached html data so this is why it will show 2 column instead of 1 column in mobile view just now.
We had helped you to clear cache and it should be working fine now.
Since you are using mod_pagespeed on your server, I would suggest you that no need to use the cache system is because mod_pagespeed should be enough to make your site performance load faster.