Immediate fix by SWE can only be released after it is tested and canaried, so it's not really "immediate" most of the time.

We run factories and if we had a bad deploy bring a factory down, it's not going to get "more broken", so we can push a fix-attempt change live as soon as it's ready.

Abstractly, we got pushback from QA about this policy. After we had gathered a couple of concrete examples, it was clear that QA-as-gatekeeper when the factory is already in the worst possible state wasn't valuable. We do mandate the normal reviews but allow them after deployment. (You can imagine the conversations with the auditors about this as well, so we had to carefully document that this was our process and made the auditors audit our conformance to the process not to their own preconception of what it should be.)

That is not true. Production fires tend to skip canaries in a sizable amount of cases.

It's especially not true when big amount of money is at stake. (like ads).

Edit: last sentence.