This is annoyingly vague. What was the software bug, and what was the valid customer configuration change? It's perhaps a bit premature to demand it at this point, but I'm hoping a full post-mortem will outline precisely how this change was not picked up in pre-prod. Surely all valid customer configurations must be tested prior to rollout.
It's not just annoying value. It's insultingly vague. If my data centre provider suffered a complete outage, then I demand to get a detailed post-mortem of what happened (in due time). If they just tell me bullshit PR speak about "We value our customers", I'll be looking at switching providers. As a Fastly customer whose site went down, I'm entitled to know exactly what happened. If they don't tell me, I'm switching…
Does your contract say you're entitled to an RCA?
As others have said, this is more of an update, not a complete RCA on the entire situation. They have short term tasks that they've described in this summary post and I would expect that they will give a more complete analysis later.