Just adding my name to the list in the hopes that Samsung realizes how big of a problem this is.
I have had my Gear S3 Classic for a couple months, and it started having rapid battery drain Monday, October 15. No change in usage, and battery life went from days (~3+) to hours (<8).
I assume my phone and/or watch updated (I had them on Auto Update), but I am not going to put all the extra effort into troubleshooting... I bought a "smart" device so I don't have to do that!
battery comletely drained after 6 hours on S3 classic should be named samsung unwareable instead was working fine before the last update now its useless to carry around a black screen that doesnt even tell me the time.
Same problem here. Used to have 70-80% battery left at the end of the day. Now the battery is dead after 10-12 hours. Started happening on Monday, October 15. Did a factory reset, but didn't help.
Same thing happening to me start Oct. 15th, I put the watch into DND overnight went to bed with 78% battery woke up with 14% battery. I have reset the watch and re-installed all phone apps disabling most all notifications and communications except bluetooth, still seeing about 8-9% battery drain every hour. Also seeing increased battery drain on the phone (Pixel2 XL) Samsung framework background activity seem to be the app using all my battery.
Having a similar issue to everyone else - went from getting about 48 hours of active use (20,000+ steps a day) to the unit dying in my sleep.
Another observation I'm seeing, when navigating settings it's appearing as though the unit is having software crashes, just going through settings (refreshes to main watch face and all other screens show "Loading..."). Samsung support was zero help.