Another important event that happened during this time was the opening of Switter in the Mastodon network. Switter.at is a new instance for sex workers who have been exiled from US-controlled web services due to new US laws. Switter quickly became one of the top 5 largest Mastodon servers in the first 2 weeks of its existence. I have given some interviews related to this, and was quoted on XBiz and Buzzfeed.
I have moved mastodon.social to a new hosting provider, with capacity upgrades. The setup is still relatively cheap for the number of people it's serving, but it's a lot more high-availability now. We are now on Hetzner with 4 EX40-SSD machines. The database has a hot standby failover, which is also used as a read-replica by some of the code to reduce load on the main, writeable database. We are now using two different redis servers, which is a new option in 2.4, since the caching layer is more volatile and completely separate from the rest it can be easily split off to reduce load. mastodon.social feels really, really fast now, and the machines are barely utilized. Room to grow.
While not something that I have done myself, I'd also like to point you to additions to the ActivityPub universe: Misskey (similar to Mastodon, but written from scratch and resembles web Twitter more), Funkwhale (a federated music streaming platform) and Plume (federated Medium). There is also a cool new webapp for Mastodon called Pinafore, which is very very lightweight and has a single-column layout. All of them are great news for the future of Mastodon.