One note, I used the images of the chips themselves and the M2 chip is physically bigger than the M1 chip by 21.8%, but the article claims a 25% increase in tra

One note, I used the images of the chips themselves and the M2 chip is physically bigger than the M1 chip by 21.8%, but the article claims a 25% increase in transistors. So there's only an actual 3% increase (1.25 / 1.218) in the transistor density with this new process. Most of the advancement is presumably in the form of better heat transfer and cheaper silicon per unit area.