To summarize the situation very briefly.

The company jumptrading has significant positions with leverage in the Japanese market.

The collapse of the Nikkei (second biggest dump in its history) triggered massive margin calls.

In disaster, its subsidiary Jump Crypto liquidated $500M of ETH in order to consolidate its stock market positions.

As the crypto market cannot absorb so many sales, it loses 15% in a few hours.

Note that Jump Trading is known for helping Terraform Labs manipulate the price of UST. In the process, they pocketed more than a billion dollars