Nina Raemont/ZDNET ZDNET’s key takeaways Oura Ring 4 users report shorter battery life. The claims come a year after its debut.  Oura seems to be quickly responding to this issue.  When Oura unveiled its fourth-generation smart ring last October, its eight-day battery life was a major draw for those upgrading from the Oura Ring 3. But a year after its release, it seems like that eight-day battery claim is weakening.  Reddit users on the r/ouraring forum report that their smart rings are...