They must pay the producers a negotiated rate to carry the content, even if Disney are the producers. So Disney+ must pay Disney Animation Studios, 20th Century Studios, Touchstone, Disneytoon, etc. and all the affiliated producers of the content, which triggers profit sharing payments and residual payments.
I never thought about that until they started pulling content OFF Disney+ to reduce the losses, and they explained why they were doing it.
Personally I think they should move to a VOD model with low rental rates for obscure content rather than pulling it off.