PANews reported on January 12th that Mempool data shows miners mined a half-empty block at Bitcoin height 878889, with only an 87-second interval from the previous block.
The founder of mempool, @mononautical, commented on this by saying that all transactions in this unfilled f2pool block were broadcasted around one minute prior. This indicates that the node creating the block restarted without a mempool.dat file or had not yet begun loading it when requesting the template. The last time a similar event occurred was at block height 855363, about five months ago.