It's likely timestamp miner put into block, not when block was received, can be off for hours.

A block is allowed to have a timestamp strictly higher than the median of the last 11(?) blocks.

Timestamps are difficult in distributed systems.

A block’s time stamp is valid when it's greater than the median of the last eleven blocks and less than the evaluating node’s current time plus two hours: https://bitcoin.stackexchange.com/q/915/5406

Timestamping is hard

That's interesting.... from mempool's doc:

When a new block is found, mining pools send miners a block template with no transactions so they can start searching for the next block as soon as possible. They send a block template full of transactions right afterward, but a full block template is a bigger data transfer and takes slightly longer to reach miners.

In this intervening time, which is usually no more than 1-2 seconds, miners sometimes get lucky and find a new block using the empty block template.