When I work from home and start late (a lot if my team is in CA and I am east coast) I don't stop for lunch of I just eat in anyway. Eating out is an office thing to me unless I meet a friend which I only do maybe once per week.

I have complete flexibility in my work hours, and have stabilized at 2h in the morning, 5h-6h in the afternoon. The morning hours are used to close tickets, answer emails and other sub-15min tasks. Afternoon is for zoning in.

Those who start working about 10am often don’t choose to completely stop work for lunch unless required to do so.

Or they have their lunch a bit later, like 2pm. You don't have to have lunch at noon.

Yep, I usually eat lunch at my desk and work straight through until a late afternoon nap.

Do you have any proof of that?

Personally i often start work at 10am after a breakfast, so by 12am i'm just not hungry yet.

Nope; just personal observation.

Well there are things to do that aren't deep-thinking coding. Interfacing with team members, running errands, interviewing candidates, etc.