DIAGNOSIS The advertised battery life assumes ideal conditions: few events, moderate temperature, and good signal. In reality, frequent recordings, extreme cold, a weak Wi-Fi signal, or the spotlight being on a lot will murder the battery.
FIX First, optimize your settings. Lower the video quality to 'Standard' instead of 'Best' in the device video settings. Increase the 'Retrigger Time' in motion settings to 30+ seconds so it's not recording a new clip every time a leaf blows. Most importantly, ensure your Wi-Fi signal at the camera is 'Good' or 'Excellent' in the Device Info menu—a poor signal makes the camera work much harder.
IF THAT DIDN'T WORK The battery health itself might be degraded, especially if it's been through many charge cycles or left in extreme heat. Try a different, known-good Arlo rechargeable battery (model VMA3700) to see if the problem follows the battery or the camera.
HEADS UP In winter, lithium-ion batteries can temporarily show a much lower charge and die quickly. If possible, bring the camera inside to room temperature to charge it fully, and consider a weather-resistant housing or a solar panel charger (Arlo model VMA3600) for a permanent fix in cold climates.