Just updated to Leviathan, why do some Aboriginals have 25 development?

I kept to 1.30.3 for a while after the initial Leviathan mess, and have only now updated it to the latest of 1.31.4, sweeping east to find that Larrakia and Yolngu have 20 and 25 development respectively in their single provinces.

Since I'm new to the Leviathan era of patches, I'd like to know, is this a known issue? I have seen some posts here and there, but only arguing about them being nation-states and not about development.

It also appears that Indian kingdoms have made contact with them prior to the 1500s... Not to mention they have fully embraced the Renaissance.