Nitpick: a mountain lion isn’t a lion; it just looks like a female lion, leading to confusion when they were first seen by Europeans in the Americas (https://www.quora.com/Why-is-the-cougar-or-puma-called-a-lio... has a nice pair of photos)

The Wikipedia page also has weak evidence for lions being involved in surplus killing. It has two footnotes. http://www.aimspress.com/article/10.3934/mbe.2018031 is a simulation, and the abstract (article is paywalled) of https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1... only mentions “foxes, spotted hyenas and other carnivores”, and hints it may only happen when prey is easily available (as with a fox in a hen house, I suppose)

I think neither article claims it happens regularly.