You're right, but I'd argue this problem is already here.

Thanks to glaciers melting, earth rotation is (temporarily) accelerating. Because of that, positive leap seconds, regular before, didn't happen since 2017 - so there could very well be (recent) software out there that has that code-path broken, and nobody noticed yet.

And due to exact same geophysical effect we might see a negative leap second - something that never ever happened before. What are the odds that every single piece of software gets that one right?