In the US, I went to a university (sarcastically referred to as find another university) where the mascot was the burrowing owl. They build nests in the sandy soil in Southern Florida. They are becoming endangered due to feral cats hunting them. And there is always some battle between preservationists and crazy cat lovers.
https://en.wikipedia.org/wiki/Burrowing_owl
Cats have a hunting instinct. No matter how well fed, they will continue to hunt. I remember living with a woman who rescued ex-breeder cats, which were all very fat. They still tried hunting lizards even being so fat that their belly hair rubbed off on the carpeting. Cats are not quite as bad as adult raccoons (who will kill every chicken in your coop just to eat one), but are not capable of hunting only what they need to eat.
The linked article says 90% of the mortality is caused by un-owned cats. I'd imagine that feral cats just replace wild cats in Europe, and thus do exist in the ecosystem with negative feedback (if they are not fed). Not sure about North America, as there is not really a small wild cat species I think?
1 https://www.tandfonline.com/doi/full/10.1080/00063657.2021.1...
Asking us to prove that cats killing wildlife is a bad thing.
A guy once told me that they remove the fallen logs from the Canadian forests because fallen trees are messy and ruin the forest. How do you even respond to such a stupid concept?