F2Pool has produced multiple blocks like this recently - are they filtering in some manner?
Discussion
No. They found it within a couple seconds of the previous block being mined.
The other block I'm thinking of (855363) had over 1 minute between blocks and included over 1500 transactions. Normally empty template blocks are just the coinbase output.
It seems like there blocks include very few OP returns and also very few old transactions (greater than 2 weeks). It's possible they are working from a significantly different memory pool or one which got whiped and restarted.
They also just produced another one with poor health 15 mins ago (855415)