I have been fucking with this all morning thinking it was something we did (we actually were changing some permissions last night / today), how about an email? There was no push of this info, I shouldn't have to opt in to that.
We have two slack channels here. One is where our internal monitoring agents post, as well as an RSS subscription to the GCP status board. We have a separate channel for less critical things (like GitHub).
Unfortunately, it does depend on GCP updating their dashboard. However, to date, we’ve only been impacted by one of these major outages. This morning, I saw the alert in our channel, but all our things were still operating (fortunately!).
YMMV, but I’ve found this very helpful.