/dev/urandom and /dev/random follow the same bit generation routine except that /dev/random blocks when the estimated entropy in the input pool falls too low.

/dev/urandom and /dev/random follow the same bit generation routine except that /dev/random blocks when the estimated entropy in the input pool falls too low. The SoCs on phones often have HWRNG support, they just don't always use it, or someone forgets to actually seed their entropy pool with it because they assumed some other bit of code would, which seems to be what happened here.