Block level deaklock issue could happen when HCC is enabled.

Hybrid Columnar Compression(HCC) is the way Exadata compresses the data. HCC utilizes a combination of both row and columnar methods for storing data.
A logical construct, called the Compression Unit (CU), is used to store a set of compressed data.

Apparently, a deadlock issue is related to resource contention between 2 actions.
Then, what could be the resources in this case?

At first, you can think of the real row-level contention.
Normally, it results from the abnormal Application design or replication product defects.

At this time, I would like to focus on other resource-related deadlock issues(block-level contention).