Home of the Joomla! Content Management System
It's a version of the logo for a somewhat popular CMS. I'm guessing Reddit automatically grabbed it from some site somewhere that hadn't bothered to customize all the various and sundry icons.
NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.
Is Joomla dying, and if so, where are developers going?
1 project | reddit.com/r/joomla | 20 Jun 2022
Joomla-Cms - Home of the Joomla! Content Management System
1 project | reddit.com/r/github_trends | 30 May 2022
راه اندازی وب سایت استیج در سافتاکلوس
1 project | reddit.com/r/u_mashhadhost | 18 Apr 2022
Top open source content management systems
1 project | dev.to | 6 Feb 2022
Best CMS for editing on mobile
2 projects | reddit.com/r/webdev | 6 Jan 2022