When you use the silverfish ability to become a block you replace the block such that when you return to the state of being a player the block is just gone. This is a little annoying for things like dirt and grass blocks, but for tile entities like chests you lose all the items in the chest.
Minecraft 1.12.2 forge-14.23.5.2847 changeling-1.2_golem-1.12.2.jar
When you use the silverfish ability to become a block you replace the block such that when you return to the state of being a player the block is just gone. This is a little annoying for things like dirt and grass blocks, but for tile entities like chests you lose all the items in the chest.