I was running the beta version of Google Play Services, and also using GBoard and Google Messages instead of the default keyboard and message apps.
All of these seemed to conspire together to make my phone heat up, have strange apps taking up my battery, making my Watch 4 disconnect, the Wear app glitch out.... so many problems with my watch and battery that I spent all weekend trying to fix.
I finally reverted back to the regular version of Google Play Services and the Samsung Messages and keyboard and now everything seems great.
So I guess I am saying that because we all have so many different apps installed, various customizations, etc that might not play nicely with the 4.0 beta, it may take some tweaks to get problems solved if you're having trouble.
A major pain in the butt, definitely, but glad to finally not have those battery problems and not have to reset my watch for the third time in a day.
I mainly use Good Lock programs and Google Messages. Only apps that take from my battery are Snapchat and Instagram (although their usage has not changed since One UI 3)
My battery got better with One UI 4, giving me two extra hours of screen on time. 85% charge giving me 8 hours!
