While you have not changed the way you use your iPhone, it is likely that third party apps have been updated in the background that did change your battery consumption. Meta apps have been seen as problematic with their use of background processes draining the battery and most of them have been updated 10 times in just the last month. Some of these updates were to address bugs, but also introduced additional ones. Go to Settings > Battery, and scroll down to view the apps battery usage over the last 24 hours and post a screenshot of what you see there.
When you say it is a new battery, is this one that was installed by Apple or Authorized Apple Service provider?