In the last few days, all the servers have been upgraded to the latest Mailman 3 code.
This is mostly a security release, closing vulnerability in Django [1]. All the latest fixes and improvements, which have been prepared for the upcoming release of Mailman version 3.3.6 [2] and Hyperkitty version 1.3.6 [3], are also included.
If you experience glitches in the Postorius/Hyperkitty UI, please perform a hard refresh of the page in your browser.