When using the COPY command to load data into Snowflake, if a column has a default value set to CURRENT_TIME() or CURRENT_TIMESTAMP(), all rows loaded by that specific COPY command will have the same timestamp. This is because the default value for the timestamp is evaluated at the start of the COPY operation, and that same value is applied to all rows loaded by that operation.
References: This behavior is consistent with Snowflake's documentation on the CURRENT_TIMESTAMP function, which specifies that the timestamp is captured at the time the statement is executed1.