Yeah i think it is a little strange, because as far as I remember the agreement of the open relationship is until Lydia is ready to have sex, so if we go to a canon way to describe her whole personalitty it is the LC cage, and it may change because she is introduced into the relationship the MC has with AmRose so it can be hinted to probably you can develop in the future a 3-way Relationship with the 2 of them
That part feels rushed af with how the relationship between the mc and her is developing, like she hasnt even give him a Handjob but strated to have fantasies of other 10 men is developing her from 0 to 100 in a second, so it only would make sense if she is behind the app or knows something about it
It could also be a fucking joke about the name of the cage, if I remember correctly also, I think AmRose or someone marked Lydia as Vanilla, so we need to wait more of week 3 to see how it develops, but for now for me the canon choice is the LC cage.