In the protocol inspector is that it states that index values for COMPACT_ARRAY and COMPACT_STRING types should be VARINT (which uses zig-zag encoding).
It should say they use UNSIGNED_VARINT (which does not): Apache Kafka
Here is an example, but as far as I can tell every instance of COMPACT_ARRAY and COMPACT_STRING in the various binspec pages for different messages has this mistake.
COMPACT_ARRAY example: BinspecVisualizer