I am a programmer and I think I can explain this bug.

Autofocus is probably choosing to sample the scene X times a second or something. To do this, it would read the system clock to dtermine how much time has passed to see if it should take a new sample. This clock would measure time in milliseconds, and the result here is probably stored in a long integer.

A long integer can have a value from −2,147,483,648 to 2,147,483,647. If you multiply 1000 milliseconds in a second, by 60 seconds in a minute, by 60 minutes in an hour by 24 hours in a day, you get 86400000 milliseconds in a day. And if you then divide 2,147,483,647 by this, you get 24.85.

The problem would likely occur when the millisecond timer goes negative. Their algorithm probably can't handle that, and either fails to take several samples as needed, or takes too many too rapidly.

At least, that's my best guess. I can't see any other reason to use a timer, and the timeframe for the rollover there being so close to their quoted time seems too unlikely to be a coincidence.