[cydonian_monk]

I suspect this is for a few reasons, and somewhat agree with your conjectures.

One of the reasons being the platform's popularity and quality of work, which has allowed them to attract higher quality talent (which in turn costs more). Another reason is anticipation of an increase in royalties/residuals as a result of the end of the writer's strike and the eventual conclusion of the SAG-AFTRA strike.

And finally because the Apple TV platform now has considerable more content than it did at launch, and can command a higher price.