In my post-mortem I go into this a bit: someone had actually triggered the bug (on accident while debugging the Etherscan block explorer) but it hadn't been not

In my post-mortem I go into this a bit: someone had actually triggered the bug (on accident while debugging the Etherscan block explorer) but it hadn't been noticed by anyone (and the person at Etherscan didn't realize the ramifications). I believe, due to the atypical mechanism used to store the account balance state on Optimism (which is discussed in detail in my post-mortem as this is also what I claim to be the root cause of the bug), it would have taken quite a long time to notice someone taking advantage of this issue if they weren't being egregiously ostentatious with it (and even then it would have taken "too long" before tons of extremely-difficult-or-arguably-even-impossible-to-unwind economic confusion and damage would have resulted as the whole ecosystem is so heavily automated).