Cat crap is the bane of the garden. My mum once saw an up-the-road-neighbour walk down the street and lean over her neighbour’s fence, and drop the poor creature on the garden to do its business! It was actually being taught to crap in another garden!
If they’d done that to me I’d be so angry I’d have bagged it all up and posted it through their letterbox (or at least, I’d have left it on their doorstep with a note).