Apple Watch series 6 draining battery

my Apple Watch suddenly got to battery drain.Also I ve noticed that to get hot in charging. There is no issue to charge the watch ,as it comes to 100% as soon as it used to.

the health of battery appears to be 94%.it’s been a year since I bought it.

i tried to fix the problem by resetting both my iPhone and watch to factory settings ( I didn’t erase the apps) .

I took it to serviced and I was told to change the battery. I didn’t and I addressed to an other authorized service provider who talk that I can’t change the battery, but give my watch back and buy a new one paying the battery cost ,if my battery health is above 80%’ .

do you know how to solve the problem?