It literally says "first" in the upper right hand corner of the image indicating the red seats, which are clearly not as nice as the purple seats, aka Delta One?
That is a composite image, with screenshots from two different pages (and I'm virtually certain from two different flights), not a legend of the seating chart and a seating chart.
I can't find an ATL-SFO flight offering Premium Select and in fact couldn't find a domestic Premium Select flight at all, but on flights where I can find Premium Select, such as BOS-AMS on May 10, 2026, here is the fare selection screenshot from that flight, and the seating chart screenshot, including the legend on a single page:
Notably, neither of those use red for "First Class" and there's no confusion between trying to use a legend from one page/flight as a key to understand a seating chart on a different page/flight. In fact, they both use red for "Premium Select" and booking Premium Select on that flight gives you a fare class of "A", which is specific to Premium Select (and NOT to First Class/Delta One, which share J, C, D, I, and Z, because Delta One is just a branding of First Class, rather than a cabin distinct from first class).
That is a composite image, with screenshots from two different pages (and I'm virtually certain from two different flights), not a legend of the seating chart and a seating chart.
I can't find an ATL-SFO flight offering Premium Select and in fact couldn't find a domestic Premium Select flight at all, but on flights where I can find Premium Select, such as BOS-AMS on May 10, 2026, here is the fare selection screenshot from that flight, and the seating chart screenshot, including the legend on a single page:
https://imgur.com/a/Nz1FxOT
Notably, neither of those use red for "First Class" and there's no confusion between trying to use a legend from one page/flight as a key to understand a seating chart on a different page/flight. In fact, they both use red for "Premium Select" and booking Premium Select on that flight gives you a fare class of "A", which is specific to Premium Select (and NOT to First Class/Delta One, which share J, C, D, I, and Z, because Delta One is just a branding of First Class, rather than a cabin distinct from first class).
Delta fare class codes: https://www.nerdwallet.com/travel/learn/delta-fare-classes
I'm not saying that there was a specific intent to deceive with that prior imgur link, but I think the end effect was deceptive.