It’s been a while since I’ve read the novel, but I believe she’s known about her powers since either immediately after or shortly after being summoned. God straight up tells her about it. Basically she gets powers from having sex with people, which is why her ass got better (one of the dudes she slept with has a Thick Butt perk or something like that). She can turn on or off all her skills/perks, but has all the combat-related ones turned off at the moment. As I said, I read the book around two years ago so I might be misremembering some details.