Sparkpool, an Ethereum mining pool that has recently mined an ETH block with a reward worth over $300,000 thanks to a transaction with a 2,100 ether fee attached to it, has recently revealed it’s freezing the funds.

The amount received is currently worth roughly 600 times the normal ETH block reward, which stands at little over 3 ETH, at press time worth about $433. Every block on the Ethereum blockchain is programmed to award 3 ETH, along with fees paid for transactions included in it as an incentive.

Block 7,238,290 included 210 validated transactions, and saw Sparkpool receive 2,103.1485 ETH thanks to the mentioned transaction, according to Ethereum blockchain explorer Etherscan. While some members of the community believe it might’ve been human error, others point to potential ways to launder money, or a sign of support for the blockchain’s miners.

The mining pool has notified its miners in a statement that it will hold on to the ether, while waiting for the entity behind the transaction to clarify whether it was an error or not. The statement reads:

We have temporarily frozen this fee and are now waiting for the sender to contact us for a solution. If the sender does not reach out in the next a few days, Sparkpool will then allocate the fees to miners who are entitled to the reward.

Sparkpool’s CEO, Xin Xu, reportedly told CoinDesk via WeChat that the organization is holding the funds over the significantly large amount involved in the transaction, and that its users and miners understand the decision.

Xu added that “fortunately, blockchain is so far not completely run by machines; humans are still involved.” This, he said, allows the pool to correct the problem, as integrity is its priority. So far, it isn’t clear whether the 2,100 ETH fees were a mistake or sent on purpose.