The new 1.13 update that was released just a number of weeks ago adds many new blocks and items to the game, enhancing the overall gameplay experience and adding on to the number of possibilities that can be achieved in Minecraft.
This must mean that there are less limitations for texture pack developers and map makers, right?
Well, the new update also brings in a number of changes that completely break some aspects of certain resource packs. A seemingly small change, or a "fix", per se, to a glitch that was first introduced back in 2016 as bug MC-109087 suggests that certain blocks such as slabs, carpets, and repeaters should cull the ground block they're on. This means that the block they're on isn't rendered as they're covered by their respective blocks. This implementation is aimed to increase the overall performance of the game, making the game less "laggy" as there are less blocks being rendered. Now, this would work perfectly fine in pure vanilla Minecraft, but is a nightmare for resource pack developers who incorporate models into their packs.
For example, a repeater modeled to look like a laptop computer worked perfectly fine before 1.13, since the ground underneath it was rendered. Now that the block underneath isn't rendered, you can see through the ground the model is on. Example below.
I've noticed that this "fix" affects a wide range of blocks, including extended pistons and enchantment tables. Since many developers use these blocks to make models, the update effectively breaks almost every single block model in every resource pack. The only blocks that you can model without breaking the ground include anvils, ladders, etc. and is a huge limitation for vanilla map makers. Therefore, my suggestion is to add an option that enables or disables back-face culling (that can be changed in the block .json file?) for the blocks underneath each block model. Culling can be enabled on default, but an option to disable it for certain blocks should definitely be implemented to make Minecraft the game of endless possibilities it was intended to be.