https://www.theguardian.com/technology/2023/dec/18/apple-watch-sales-pause-patent-dispute

Sales of Series 9 and Ultra 2 watches affected amid dispute with Masimo over technology behind blood oxygen feature

Apple said on Monday it would pause sales of its Series 9 and Ultra 2 smartwatches in the United States from this week, as it deals with a patent dispute over the technology that enables the blood oxygen feature on the devices.