What? No they aren’t. They almost always fail on a curve of power and voltage loss.
Also, I didn’t look it up, but I’d be very surprised if the model Y tesla didn’t require (suggest and oem?) an AGM battery. It’s still lead, but due to how they’re made they can’t get a dead short in them like older regular lead acid batteries can once they get old, although it still isn’t very common for it to happen.
No they aren’t. They degrade before they fail. If tesla wanted to provide a warning of a failing battery that pretty much always worked it could have wired in a load test and went off voltage drop under a heavier load.
Testing if batteries are good or bad does not qualify a person to chart out battery degradation.