As devils advocate, maybe this is evidence such QA doesn’t matter as much as everyone thinks? It looks like no actual damage was done and the problem was fixed quickly once users noticed it.
Sure, using your users as QA is a fine business plan and instills confidence. We should extend this to other expensive industries (healthcare, law, civil engineering, etc.).
It seems fine for social media
Testing is necessary even for social media, not doing so is a big security threat for its users. Even apparently dumb bugs like this one can be exploited to steal important information.
Social media may not seem as important or vital as banking or healthcare, but most of our modern society depends on it. Socials are the best tools for social engineering after all.