Production of the Apple Watch Series 9 and Apple Watch Ultra 2 will cease due to an ITC import ban caused by a patent dispute between Apple and Masimo over a pulse oximeter sensor. Masimo is a manufacturer of medical devices. The ban applies specifically to United States customers. The pulse oximeter in your Apple Watch tells you what your pulse and blood oxygen levels are. The Apple Watch SE does not have this sensor, and is therefore unaffected by the ban.
Standalone pulse oximeters do cost far less than Apple Watches due to the fact that they don’t offer as much functionality. However, smartwatches (especially the Apple Watch) have gotten popular. This means the watches will surely eat into pulse oximeter sales if they haven’t already. People are far less likely to buy a pulse oximeter if one is already built into their watches.
Smartwatches also log and graph the history of your health measurements over time. This is something that a pulse oximeter can’t do as well because it isn’t designed to be worn all the time. Whether or not Masimo’s dispute is motivated by the Apple Watch’s success — it is surely a threat to their business.