This is a very popular Lemmy.World community. This instance has been dealing with regular ddos attacks for quite a while now. Either some person or some group has an issue with this specific instance, or they picked it because it’s the biggest and they’re trying to take Lemmy down generally. The ddos attacks have chased away a number of people, but lots of us have dug in our heels. This is probably the newest strategy.
The admins have said, based on the ddos strategies, whoever is doing it is familiar with underlying Lemmy implementation, so my guess is it’s someone from one of the instances that we defederated from, but it’s just a guess.