Why is the tube too long? My current tube was badly pierced by a screw in the street, so I wanted to replace it with a new one. The tire is a Continental 32 - 622 (28 x 15/8 x 1 1/4 - 700 x 32c), so I bought a 28" tube, exactly this one. (Actually I said in the shop that my tire was a 700 x 32c and they gave me the 28", which made sense at the point).

Then, when I put it in the wheel, it was obviously too long (excess length). How comes? Shouldn't a 28" tube fit perfectly a 28" tire? I got a 26" tube and it fits better. I'm very confused.

PS: The pierced tube was also too long, as it was folded. It's a second hand bike and it's the first time I've taken the tube out in 4 months.
That does not look like a 28 decimal
That is a 28 fraction and that is not a 700 (622)

Sheldon Tire Sizing