Is Twitter/X the right channel to announce a security event like this? I ask because I don’t see anything posted on their official blog or status page. https://github.blog/ https://www.githubstatus.com/
It's been pretty common in the past for tech companies to announce outages and quick updates about them on twitter for decades. I'm sure their status page etc will be updated soon, but it's historically been the fastest way to get things out to the wider audience whilst bypassing the "official mail out" review by marketing etc.
Most individual permalinks (.com/username/1234...) don't work without logging in, either, and the official client now uses `/i/` in place of usernames for permalinks(bogus usernames always worked; pkey was the timestamp).
This means an organizationally shared Twitter account for announcements is not a viable concept, at least until Twitter is to be transferred again to whoever would be a better keeper of it.