The wording of H.266 B.3 seems to require byte streams to start with at least three zeros

[dreifachstein]

Quoting B.2:

... is such that the next four bytes in the bitstream form the four-byte sequence 0x00000001.

Yet RAP_B_1.bit starts with only two zeros.

The same discrepancies exist between H.264/5 and conformance bitstreams.