I recently have made a pillager farm. It was quite ugly to look at so I built this desert temple-type pyramid to make it more aesthetically pleasing. The farm was working just fine before I built the pyramid but now the pillagers and ravagers randomly spawn on top of half slabs or stairs on the outside. This is really annoying as it completely removes the afk aspect of this farm. I was wondering if the mobs are allowed to spawn on top of slabs and stairs or if this is just a bug. As well as thatI'm not sure if they spawn on sandstone walls as well. I've looked it up and it appears that they shouldn't be able to spawn. If it is a bug, please fix this as I have spent an entire day building up this pyramid and I don't want to destroy it in order for my farm to be fixed. Thank you