I was about to post something similar. I had a look at Commits · discourse/discourse · GitHub because, to me, it didn’t feel like there was that much more activity.
I don’t think it’s any busier now than it was at the beginning of December. You can see the lower activity during and around the meetup in September and Christmas, and you can see the general increase in the summer after many plugins were integrated into the repository. Updates for these also count since then.