The title is quite self-explanitory:

Oh this is certainly weird. I kind of like it though lol

It messes with Sky Resources' Combustion chambers that currently check for the same things torches do to determine if it can be used as part of the multiblock. The Item Grate has been heavily exploited the last 2-3 months.

I don't know what the combustion chamber is, how does this allow for exploits?

It's multiblock that only works when it has solid blocks above it. The point here is that it tests for the same thing that is needed for torches to be placed, so if torches can be placed on the blocks, said blocks can be used to construct the multiblockl. You need to throw items in it and close it to start generating heat and be able to make new items. Once open, it starts losing heat. Since those blocks' models have enough space to throw the items through them, the player doesn't have to open and close it.

I am still not sure if I would call this a bug or not. I kind of like that you can use it to drop items in, since that's kind of the point of the block. It's a neat little bit interaction, and you don't really see those much anymore. I will probably fix this though.

After some consideration I decided that this was a bug, and fixed it for all of the affected blocks.