I have got samsung A7 2016 and gear s3 frontier. Everything was fine until end of november. My watches start discharging in 12-14 hours!
I did not install anything, I did not do anything, this issue starts suddenly.
Also, I noticed, people got a new software version on December, but I am from Ukraine and no software is not avalible for my watches.
gear s3 frontier - SM-R760
Can you recall downloading any new apps around the time ?
If not then try a reset of the watch in the settings after you've backed it up.
A Samsung Experience Store or Samsung Service Centre can run a diagnostic on the watch too.
Unfortunately timeframes for software isn't discussed by Samsung and it's a case of periodically checking for updates.
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.The advice I offer is my own and does not represent Samsung’s position. I'm here to help. " This is the way. "