I log everything that comes over pubsub, on all relevant topics and some unofficial ones, and fixed my parser when I got a different packet to what was usual.
In this case it happened to be during Dropped Frames and Twitch Tweeted about the feature, and pretty much instantly people started using the feature in the $channel I primarily work for. So since my PubSub Consumer logs everything, took me all of five minutes to apply a patch everywhere, patch my software client and pushed out an update to my software client within 15 minutes.
Both PubSub and Twitch TMI notice give the relevant information, you just have to read the data.