Composters work strange.

For some reason, I came up with the brilliant idea of ​​placing a block of slime under a composter, when I got into the composter it became slow, bounced and the sound of the slime could be heard.
In short, it was like walking on a block of slime. But it is not the only one, honey, soul sand, magma block, etc when placing them under a composter they also caused their effects when I got into it.