Just be cautious about assuming something is wrong with the camera. Like advanced cameras, the newer trail-cameras have the ability to monitor and adjust for the amount of illumination bouncing back to the camera. They will reduce illumination if a lot of light is coming back. This is to reduce "wash out" of a subject close to the camera. So if there is something close to the camera - deer, tree, grass, etc. - that is reflecting a lot of light, the camera will reduce how much light it is projecting with the flash. So before assuming something is wrong, test the camera where NOTHING close is reflecting light. If illumination is still poor, then there's a problem.
my older Browning are on their second year of taking hundreds of videos (some over 1,000), many at night, with the original set of batteries and they are still going strong with 96% battery power. Your battery monitor might not be wrong.