Unity is used more widely than you might think, though maybe it's just your definition of AAA here.

Mihoyo's titles all use Unity AFAIK and have massive AAA-level budgets along with massive AAA-level revenues. Most of the big publishers have teams using Unity, you can kind of pick and choose whether those individual titles are "AAA" or not but like, Blizzard ships Unity games, etc. It's become a go-to choice for stuff that you want to cheaply ship across many platforms and have run on low spec devices.