Why is my Apple Watch battery wearing down so fast

How fast is fast? How long does your watch last between charges? Apple's specs state that (except for the Ultra) a Watch should last 18 hours between charges. I get more than that unless I'm working out. Then it drains more quickly. If the workouts were long, I might get less than that.

Also, how old is your watch? As batteries age, they last for less and less time between charges. On your watch, go to Settings>Battery>Battery Health. What is the percentage shown for "Maximum Capacity" ? If it's below 80%, your battery is past its useful life.

I don’t know how you’re measuring a fast battery drain, but for comparison my watch 8 with GPS lasts for about 36 hours with 10% to 30% reserve.

I’ve noticed this too recently. And so has my wife whose Watch is barely a week old.

Mine started after update 10 I’m worried the battery will be affected by the software update