As the title says the vomit is deleted by the airflow tile. The vomit surrounding the AF tile is from when the dupe vomited on the regular tile on the left, but when the dupe's vom reached the AF tile it instantly disappeared, and in the image it shows the vomit being instantly deleted before it reaches the ground.
I thought that maybe it was simply being pushed off the AF tile, but this was not the case, the mass of the surrounding puke was not increased and it did not spread.
This could be just a one time issue but this issue did not occur after I replaced the AF tiles with new ones
I really don't know what might have caused this but
Step 1: move dupe onto airflow tile
Step 2: puke
Step 3: puke deletion