For the last week my Galaxy Watch battery has been barely able to last through the work day. When I check the time left on my battery life, it still shows that it has a normal amount of time left. My altimeter is also WAY off, and already registering me having walked up 5 floors when I haven't left my one floor apartment.
For proper context, I did wear my watch at the beach last weekend. It was on waterlock mode the entire time that I was on the sand. Not sure if that's part of the problem.