Good tests are documentation that a computer can verify. Because they explain the meaning of parts of the system, they contain information not available in the code. If you try using ML for test generation, you'll have the same problem you do with GPT-3 prose: it might look plausible at first glance, but lacks coherent meaning.
You'd also end up with one of the problems common in big test suites: poorly factored tests that end up being the sort of expressive duplication that is a giant drag on improving existing code. ML is nowhere near advanced enough to say, "Gosh, we're doing the same sort of test setup a bunch; let's extract that into a fixture, and then let's unify some fixtures into an ObjectMother.
For people looking to get the computer to do the work of catching more things with less burdensome test writing, I suggest taking a look at things like Hypothesis: https://hypothesis.readthedocs.io/en/latest/
I feel like you just described every developer/codebase where mock testing is stupidly enforced. Where every single unit test mocks every single indirect object. 98% of the testing code is just exhaustive setup and teardown of objects not being tested by each test, and then a bunch of conditional checks to ensure that every deeper/indirect method is being called exactly the right number of times with exactly the right arguments and returning exactly the right value. Almost all of the test code is just hacking mock objects. The actual purpose of each test is buried so deep that it's impossible to even understand the business logic being applied.
I hate evangelical "mock testers" with a passion.
When you add a Firmware Password to a Mac, you get a long recovery code as a fallback safety in case you lose/forget the password. Apple, if provided with proof of purchase for the serial number being inquired about, can create a bootable USB stick with a certificate generated using public/private key crypto for which Apple holds the private keys.
I suspect much of this newer functionality acts as a replacement for the Firmware Password, giving more options and making it a bit more well-known.