The SRFI in the description of (make-default-comparator) says:

 > When comparing bytevectors, it must behave the same as a comparator
created by the expression `(make-vector-comparator (make-comparator
bytevector? = < number-hash) bytevector? bytevector-length
bytevector-u8-ref)`.

This expression makes a bytevector comparator that has bytevector
components. The correct version is given further up as

     (make-vector-comparator
      (make-comparator exact-integer? = < number-hash)
      bytevector?
      bytevector-length
      bytevector-u8-ref)

-- Peter McGoron