Location services draining battery

I have recently updated my iPhone XR to IOS 16.2. I am now having problems with rapid battery drain. I have been isolating services my phone uses (Bluetooth, WiFi, etc.,) to try to identify the cause and believe it is down to location services. With location services on but all apps using these when in use, the drain on the battery was reasonable. However today, after using the Fitbit app to track a short walk, the battery drained 30% in 40 minutes while the app was being used, and has continued to drain rapidly, despite the app being closed (a further 50% in a little over 4 hours.). Can anyone give me some pointers as to how to solve this?