I just downloaded a fresh copy of Brave Nightly to try out my new Origin account on it. I noticed sponsored background images are still present and enabled by default:
Since the ads are a way for Brave to earn revenue, and Brave Origin is marketed as a way to support Brave without other revenue-earning features, it might be offputting for Origin purchasers to be served ads. I think you should remove this functionality, or at least disable it by default.
Great news, as of Brave Android Nightly 1.90.121, there are no longer any sponsored ads on new tab pages, and the option to show/hide them has been removed.