Heavy battery use since I bought a Mac Mini

Hi,

I recently bought a Mac Mini. Since that time, my Apple Watch Watch Series 5’s battery drains very fast; it isn’t rare it will be spent around 3PM. Previously it would easily last all day and more.

when I reboot my Mac, the issue seems fixed for a day or two. It also has a degree of unpredictability. Some days it will be fine, others no.

I have already disabled Handoff and unlocking the Mac with the Watch. I have also wiped and restored my Watch and disabled background refresh.

what can I do?