cats lick their paws a lot, especially cleaning.
I’ve heard people use things like this, which gets on their paws. It’ll probably deter them.
You may need to replenish after heavy rain. And of course you can use the rest in cooking.
No use for me unfortunately; a garden with no fences at all, in an area where every other house has at least one cat. The kids now know to check the garden before playing.
But as the cats generally seem to use the same place on a regular basis, you can just check that place. If you clean it up, sprinkle a dash of vinegar or similar, they lose the attractive latrine smell. They will just set up elsewhere though, so when they find a place that is ‘acceptable’ just let them continue!