Currently on the Bitcoin network, the average block size is 0.804MB and there are an average of 1609 transactions per block that is why a block like 540107, which is 2.26MB big but only has 230 transactions included in it, is such an anomaly.
Anomaly? It's pretty clear that the one who wrote this is just cherry picking. Block 540107 was found ~1 minute after block 540106 which consisted of 2328 transactions. Both blocks were mined by BTC pool.
It's just Bitmain not picking up more transactions to allow nodes more time to validate the previous block properly. Don't forget that it takes extra time for Chinese miners to push blocks through the great firewall.