This is from the culture where don't show you outsourced some of your work and claim that you did everything internally. There was a time where players think outsourced anything is bad but we have since gone way past that. Many big studio out-sourced their asset making/audio etc cause it's simply too much work to do the up keeps if you don't have a library of them from your past games.

As far as I know some Japanese company still operate this way and the out-source partner are contractually not allowed to disclose what they worked on. You would be considered lucky to even make the partner list with company name only. It's a really bad standard and I hope we just get rid of that entirely. (If you are not aware, China's asset outsource companies makes a lot of assets for AAA industry for a long time. )