Our neighbor has too many cats. There are at least 5 cats in their backyard at any one time. They just keep multiplying and even "invaded" the renthouse we occupied. That renthouse is directly behind our neighbor's.
I don't know how these cats started. My feeling is the leftover food the neighbors leave outside just attracted more and more stray cats.
And they can be so noisy at night. Here's one of them I caught sleeping in a wash basin.