If you get their Payboo card you don't have to pay tax. Took me like 2 minutes to sign up. They just closed the program but are re-opening it in January.
Opening the line of credit will lower your overall credit utilization, actually helping your credit score in the long run.
Let's be serious, literally no one cares about paying tax on the rewards.
The new program is exactly the same as the old one. The backend card provider is changed.