In Jain tradition, this is not a contradiction.

If you are talking about Shri Neminath Bhagwan, then:

• He was not 80,000 years before Shri Krishna.
• He was Krishna’s cousin in the same era.
• He renounced worldly life and attained moksha in the time of Shri Krishna.

So the correct Jain understanding is:

• Shri Krishna lived in the Dwapar Yuga.
• Shri Neminath was also in that same broad time period, not 80,000 years earlier.
• The relation is often called “brother” in a broad family sense, but actually he was from the same Yaduvansha family, not Krishna’s real brother.

If someone says “80,000 years ago,” that may be a confusion with other Tirthankars or with very ancient time-cycles, not with Neminath Bhagwan.

So the answer is: Neminath and Krishna were contemporaries in Jain tradition.