The last consumption time displays as 1970 when a consumer group has not consumed the messages in one or more partitions of the data source topic.
Cause
When a consumer group has not consumed messages from certain partitions, ApsaraMQ for Kafka has no timestamp to display and defaults to the Unix epoch -- January 1, 1970.
Once consumers start consuming messages from the partitions, the last consumption time updates to the actual timestamp of the most recent consumption.