A single unconfirmed transaction is moving 554.94 BTC across the network. It is not yet in a block and can be replaced.
According to SENTINEL event ux_1oi9q39 (source mempool.space): 554.94 BTC ENTERED THE MEMPOOL. Verify: https://sentinelbtc.com/api/v1/events/unusual/ux_1oi9q39