Surely, you're joking?

I think there are individual spots that are bright or dim for no reason because of random noise, up in the no-particular-pattern wilderness

Maybe people are setting it up at home using a numberpad? In that case it would be just running a finger down the left side.

I got a PIN assigned by my bank back in the 1980s, and it is in that range. I always assumed it was random, because how easy is it to generate a 4-digit random number? But maybe they gave out PINs more like safe combinations. I don't think you could change them back then, either.

I think that's the overlap between the dense region of PINs that start with 11, 12, or 13 (similar to the dense regions that start with 21, 22, 23, 31, etc), and the dense square region of month+day dates.

Lotta baby making going on in winter months.

I think that specific block is also more likely to be a street address in a city. So it has two reasons to be common easy to remember numbers.

It's set to fade in from 0 opacity, for some sort of unnecessary "ooh look it's fancy" effect. My guess is that if you check the console you'll find that it hit some exception before it completed its little fade-in effect.