Rosanne was fired in 2018. Trump was president then. Barr posted a racist jab at former President Barack Obama aide Valerie Jarrett, comparing her to an ape. ABC pulled the plug on Barr almost immediately, despite it being their highest-rated show.
Barr alleges that Barack and Michelle Obama pressured Disney's Bob Iger to fire her, but there is no public evidence to support this claim. The decision to cancel her show was officially attributed to her controversial tweet and Disney's internal standards.