Placing a stone slab (minecraft:stone_slab) above a hopper (minecraft:hopper) is no longer pulling items through as previous versions allowed.
Also to note, dropping multiple of the same item in a block consolidates the items to a single dropped entity, and not multiple entities.
Tested with chicken eggs, iron shovel, random blocks.
This came up while building an egg farm, and found chicken eggs were not dropping through. work around is to use carpet instead, but this is a fairly large bug that will affect numerous contraptions users have designed (mob farms, passive animal farms, anything that requires a water or lava stream above a bottom sla, etc).
I uploaded (then removed and uploaded again for quality) short video clips depicting the issue as well as the screenshot.
The only notable difference that I saw, apart from the broken functionality of the hopper, was that the items are consolidating world entities into one per type of stackable item I threw.