I’d say probably the users leaving reddit due to the api changes. Iirc around the 20th was when spez did an AMA about the changes and made PR exponentially worse by using canned responses, throwing subtle insults here and there and ignoring the big questions in favor of what he’d already had his PR team write a response for. It was more rage inducing than the initial api change announcement.
I could be completely wrong though maybe that wasn’t on the 20th but feels like it was in my head canon