This sounds like a disturbingly effective idea. I'm glad that lootbox legislation seems to be increasing, but I don't think it would cover the general concept of commercially extorting people's desire for companionship.
Yeah, I guess there's no reason this really needs lootbox, it just ties it to a known-exploitive quantity. Actually "our AI model is so advanced, your AI companion is totally unique and takes up many gigabytes, we'll have to delete it if you don't keep paying" seems like it would have enough of an appearance of plausibility to trick some people.