OP assumed that Stripe would get it right exactly as they wished it would work, and wasn't verifying it. The problem literally started as soon as they enabled

OP assumed that Stripe would get it right exactly as they wished it would work, and wasn't verifying it. The problem literally started as soon as they enabled it: "I deployed it on November 6, 2021, the same day that Stripe stopped billing a significant number of my customers, left all their invoices in a Draft state, and didn’t tell me about it." This is just another variant of "cloud first" mentality, assuming that cloud service providers are actually going to be better than you (as opposed to just cheaper) in carrying out these tasks. The companies I've worked for put enhanced auditing and reporting in place before this sort of thing went live to make sure it was working right.