Since supplemental logging has not been enabled for all the columns in the table, Replicate can only capture the updated values of those columns and the pk value.
For RDBMS Target with apply changes, Replicate will update the modified column in the target table by matching the primary key (PK).
However, for a File target like S3, we have to fill all the columns in the CT table so we will write PK and updated column values in CT table and make all the remaining columns as NULL.
Hope this is clear. Let me know if you have any questions.
