Cats dislike the smell of citrus, so, spread some orange or lemon peels around the yard or make a citrus spray. You can also use ammonia-soaked rags.
This has some good ideas, we use a sprinkler sytem that spray water when they come near out plants https://www.neighborhoodcats.org/how-to-tnr/colony-care/keeping-cats-out-of-gardens-and-yards-2
Use scent to keep the cats away
How to keep cats out of the garden - David Suzuki Foundation
https://davidsuzuki.org › queen-of-green › keep-cats-garden
Cats don't like citrus plants , thyme and human hair
Cats despise the smell of citrus so put orange or lemon peels all around
Sexy....If you know who it belongs to talk with them
I would try to track down the owner.
Then what? Do you seriously think the owner can keep the cat out of the yard? Cats roam where they want to.
Interplant in the garden. Cats dislike the smell of rue, lavender and pennyroyal, Coleus canina and lemon thyme.