It's normal for event organizers to still be careful and limit and/or cancel events. There's little government action on this nowadays (although there might be some more enforcement this winter).

Germany is (sadly) not running a China-style Zero Covid plan.

Especially considering the chaos congress was, even before covid, known for the "hacker pest", a type of flu that pretty much every attendee would contract due to bringing together so many people from different regions for a week (also known as cccebola). The organizers want to avoid the same occuring with BA.5 or an even newer Covid variant.