The calendar has accessibility issues.
The module is using fullcalendar version 4.4.2.
Tab through the events on calendar, it will go through the first event of each day (Mon, Tue, Wed..) and then come to the second event of Monday and so on. Rather than going through all the events on Monday first then moving on to Tuesday.
Update fullcalendar library version to 5.10.1 or higher.
https://fullcalendar.io/blog/2021/11/accessibility-enhancements-in-v510
Closed: won't fix
5.1
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.