Forget the study, let's just do a simple thought experiment. Your developer gets paid $140k/yr (let's round up to ~$70/hr). Let's say a given bug found in testing takes 1 hour to fix; that's $70 (not counting the costs of ci/cd etc). If they miss it in test, and it hits production, would it cost $7,000 to fix? Depends what you mean by "bug", what it affects, and what you mean by "fix in production".

- Did you screw up the font size on some text you just published? Ok, you can fix that in about 5 seconds, and it affects pretty much nothing. Doesn't cost 100x.

- Did your sql migration just delete all records in the production database? Ok, that's going to take longer than 5 seconds to fix. People's data is gone, apps stop working, the lack of or bad data fed to other systems causes larger downstream issues, there's the reputational harm, the money you'll have to pay back to advertisers for their ads / your content being down, and all of that multiplied by however long it takes you to restore the database from backup (um... you do test restoring your backups... right?). That's closer to 100x more expensive to fix in production.

- Did you release a car, airplane, satellite, etc with a bug? We're looking at potentially millions in losses. Way more than 1000x.

And those are just the easy ones. What about a bug you release, that then is adopted (and depended on) by downstream api consumers, and that you then spend decades to patch over and engineer around? How about when production bugs cause your product team to lose confidence in deployments, so they spend weeks and weeks to "get ready" for a single deploy, afraid of it failing and not being able to respond quickly? That fear will dramatically slow down the pace of development/shipping.

The "long tail" of fixing bugs in production involves a lot more complexity than in non-production; that's where the extra cost comes from. These costs could end up costing 10,000x over the long term, when all is said and done. Security bugs, reliability bugs, performance bugs, user interface bugs, etc. There's a universe of bugs which are much harder/costlier to fix in production.

But you know what is certain? It always costs more to fix in production. 1.2x, 10x, 1000x, that's not the point; the point is, fix your bugs before it goes to production. ("Shift Left" is how we refer to this in the DevOps space, but it applies to everything in the world that has to do with quality. Improve quality before it gets shipped to customers, and you save money in the long run.)