Note: this was actually tested in 1.16.100.57

On 1.16.40 I created a single farmland block crop farm, which works for Wheat, Carrots, Beetroot and Potatoes (see screen shot). It uses dispensed bone meal to grow the crop and a villager to harvest and replant. The farm continues indefinitely, with the villager replenishing the seeds/crops to replant into its inventory and any spare being collected by a minecart with hopper embedded in the farmland block.

On 1.16.100.57 the villager harvests crops, but does not retain sufficient crops in its inventory to replant, so after some time the farm stops producing. I set the villager up as follows (for potato farm):

1) New villager with empty inventory.

2) Give him a bed and a composter to make him a farmer

3) Trade with the villager to lock in his profession

4) Break the bed and composter (he doesn't need them in 1.16.40)

5) Give the villager 1.5 stacks of potatoes (2 inventory slots)

6) Give him 1 beetroot, 1 wheat, 1 bread, 1 wheat seed, 1 beetroot seed (5 more slots), so the villager has one empty slot still. I don't think the empty slot should matter, I'm giving him the other things to maximise output, so he doesn't fill his inventory with the crop I'm trying to produce.

7) Leave villager on the farmland with his head in a glass block.

What happens on 1.16.40: Villager plants potatoes, harvests potatoes and my collection system gets over 1.5k potatoes per hour. Runs indefinitely as villager replenishes his inventory with harvested potatoes

What happens on 1.16.100.57: Villager plants potatoes, harvests potatoes, but doesn't collect enough potatoes to replenish his inventory. After he runs out of potatoes, he plants the carrot, beetroot seeds and wheat seed and then the farm stops. I've confirmed with Universal Minecraft Editor that the villager has no potatoes left in his inventory.

This may be related to the change to optimise harvesting, but that appears to have had the opposite of the intended effect.