Fast transfer, 1-2 seconds.

How is it possible that an address is receiving, for example, 1 ETH, and within 1-2 seconds, it is already being transferred to another address? I tried to make a script that automatically checks for the balance, but the fastest I could achieve is 12 seconds.

Why am I asking this? I found a private key (it was the txhash from a testnet, and I was curious to see if it would work as a private key). The address I discovered is constantly receiving small amounts of ETH (0.0000000…) and instantly transferring them to another address. I searched for the address, and all the results pointed to crypto scams. A few people who got scammed mentioned that their funds somehow ended up at the address I found.

Not only on Ethereum, but this address is also receiving amounts of tokens on almost all EVM blockchains.