It seems normal because even on an old raspbian Rpi3 I get the same answer when I should get BCM2837 so how to get “directly” the correct answer ? (without computation if it is possible)
Note: As of the 4.9 kernel, all Pis report BCM2835, even those with BCM2836, BCM2837 and BCM2711 processors. You should not use this string to detect the processor. Decode the revision code using the information below