I wasn't having any issues after updating to watchOS 10.0 (or any of the sub-updates) outside of the weather complication glitch, but just updated yesterday to watchOS10.1 on both my Apple Watch Ultra and my wife's Series 8. We couldn't get past the 80% charge (even after turning off Optimized Battery Health in order to charge it to full last night), so when we went to sleep last night they were both at 80%. My Ultra drained to 5% in 7 hours (I would've lost maybe 5-10% over that time period in the past) and my wife's Series 8 lost all its battery and went into Power Reserve. Not only that, but I seem to have lost the ability to fast charge my Ultra (tried two different chargers).
Called Apple Support this morning - I was a bit concerned when the person I spoke with asked whether the watchOS10.1 was a beta version as they hadn't released 10.1 yet (I've never run a beta version of any of the OS on any of our devices before). She ran a diagnostic, and everything was fine (not surprised). Her solutions were either to go to an Apple Store (which seemed like it wouldn't make sense, since to me this seems like a software issue so what is an individual at the store going to be able to do), or she would issue a ticket to some internal site, and if that gets enough 'hits' or 'votes' then it will be a priority for the engineers to work on that issue in an upcoming update. I'm assuming they will be receiving plenty of calls with a battery issue that essentially makes the watch obsolete, but I'll encourage others to contact Apple Support if they're having similar issues to make sure it's on their radar. Be prepared to not get a solution, but hopefully with enough calls, the problem will get solved.
I will say I've been disappointed with the recent OS rollouts (I'm a huge Apple Fan - have all the devices), but iOS17 gave us issues with morning alarms, I saw a complication glitch with weather in watchOS 10, and this issue is huge. From here on out, I'll be thinking twice about running an update immediately (fool me once...).