I've seen a few articles about this topic, including the hypothesis that menopause is caused by reproductive competition between females in a clan. It's something like this:
If you're a chimp, once you reach adulthood, you'll stay within your clan if you're male, and migrate if you're female. So the males in the clan tend to be close relatives (e.g. father and son), while the females tend to be unrelated.
Easier to explain by naming some chimps. Let's say that you got the following clan:
Alice - female, older gen
Bob - male, older gen; Alice's mate
Charlotte - female, newer gen; unrelated to the above
Dan - male, newer gen; Alice and Bob's son, Charlotte's mate.
Charlotte's brothers are living in another clan, with Charlotte's parents. Dan's sisters spread out too, they're living with their in-laws.
The offspring of any male in the clan is likely a relative of the other males:
If Bob has a new child, it'll be Dan's sibling
If Dan has a child, it'll be Bob's grandchild
So they carry at least some genes of the other males. This means that males need to ensure the survival of each other's offspring.
However, this does not apply to the females. There's an asymmetry here:
Charlotte's child is likely Dan's child too, thus Alice's grandchild
Alice's new child is not a relative of Charlotte. It's just her in-law.
So Alice has reasons to care about Charlotte's children, but Charlotte doesn't really give a fuck about Alice's new children.
Why does this matter? Because a chimp clan shares resources like food, and resources are limited. An adult can often pull their weight, but children won't, and often there's not enough food to feed a lot of children: if the clan has one child it'll likely survive, but if it has two both will likely die. So Alice is encouraged to lower her fertility to ensure the survival of Charlotte's children, but the opposite is not true. That's menopause - the older female stops reproducing, but the newer female keeps pumping out children.