I had the same problem with my work-issued Thinkpad. No overheating, but frequently pulling the laptop out of the bag and finding battery dead. Solution I found was to bind the power-button to "hibernate", and just using that any time I knew I was going to be putting it away into my bag.
One problem I ran into writing my first Windows Store application like 10 years ago was that Windows Store seemed to have no interest in mobile-style security where you request permissions one-at-a-time and only the ones you need - the intended workflow was that you either requested no secure privs and let your app be "untrusted", or you made your app "trusted" and requested all the privs. This was actively recommended by MS.
Of course, this means "wake from sleep" would be something that every app would have permission to do accidentally, even if they didn't want to.
I managed to fiddle around with my work Dell laptop and disable that nonsense. I think it was called "modern standby". I don't understand why this isn't considered a fire hazard. It was terrifying to leave my laptop in my backpack until I figured out the fix.
Yep, while my Extreme Gen 4 has a BIOS toggle, my work-issued T14 Gen 3 does not so I had to get IT to come in and enable hibernate. Prior to that it seemed like it had less battery life sleeping than awake. (ex: fully charged and confirmed that the power light is flashing before flight - few hours later it's 100% dead.)