This was my first thought also, but it seems like there are other things at play.
My battery doorbell went down to 20% in 30 days. My Power Manager setting was 15 second clip length with 5 second retrigger interval, with the end clip early enabled. All other settings were at default. I averaged 60 detected events per day, with about 55% filtered by AI.
I recharged the doorbell yesterday morning. I changed Power Manager setting to 10 second clip length for the video. I changed the Motion Detection Sensitivity to Medium-Low (2 out of 5).
Based on the Power Manager verbiage, the Optimal Battery Life happens when you disable motion detection and turn off doorbell LED. So if you want it to last 6 months, this is how you do it. Just use it as a doorbell and forget about security. If you want to use it for security, then it will last between 1 and 5 WEEKS.