I'm very sceptical of their claims that ~780Hz is in some way special, especially the way they represent it graphically. Playing a frequency sweep while wearing WH-1000XM3 headphones, I don't notice any particular drop-off there.
Near where I live, heavy goods vehicles are fitted with reversing indicators that make a "cshh cshh cshh" sound i.e. pulsed white-noise. White noise like that is the hardest for ANC to cancel. Sample: https://www.youtube.com/watch?v=A3Wt1_51EVA
The construction site next door is using those vehicles, and they're also a lot more pleasant throughout the day. It's easier to tune out white noise than beeping. The first cshh is a little louder than the others, which is a nice design touch.
On my wh-1000xm2, wh-1000xm3, wf-1000xm4 and lastly wf-1000xm5, there is a quite high frequency pitch (usually coincides with some public transport beeps, and some accidental squeaking of doors) that toggles ANC to transparent mode automatically. I remember reading something about this on Sony's support website.
Right? This feels like an "arms race" similar to scraping vs. anti-scraping; countermeasures will be developed, likely due to the action of actors entirely disconnected from what you're doing, but to block something else in the ecosystem... and you'll need to re-engineer your approach entirely. Rinse and repeat.
(The amount of innovation in anti-anti-scraping that's resulted from "sneaker bots" - automated scalping of limited-edition shoe releases - is astounding, and somewhat relevant here in how an environment can become adversarial in ways that impact broad ecosystems. I suppose the equivalent here would be environmental ads that seek to penetrate noise-cancellation in a similar way.)
I suppose, though, that all this is good news for a company that wants to turn your bicycle bell into a subscription product!