You probably have two different issues here.
One is probably an issue with third party software that is not needed & known to cause problems (Anti-virus app, cleaning/optimizer apps, third party security software) which will cause performance issues & the computer running hot with the fans kicking on.
The second is indeed a possible Apple issue, but not specifically tied to Tahoe because I have seen the issue with Sonoma & Sequoia. I have seen a few laptops I've been testing suddenly have their battery capacity drop from a significant value (40%) to 0% in a matter of a couple of hours while sleeping with no record of the battery draining, along with absolutely no system logs for that specific time period and my battery monitoring software had shown a consistent very slow drain for the week prior as I had the laptop sleeping. I first saw this occur with a brand new third party battery which I had already thoroughly tested, but also with an original factory installed Apple OEM battery as well (also completely healthy & passing all of my customized battery tests).
Unfortunately I have not looked into this issue since I have not had the time and because none of my organization's user have complained about such a problem. I'm not even sure I'm equipped to diagnose this problem. I don't think even Apple is equipped to troubleshoot such an issue.....the Apple engineers would need to be able to reproduce the issue themselves & I have no idea how they could trigger it (could take a long time).
Your options assuming you are indeed encountering the mysterious sudden drop in battery charge is to keep working with Apple & once the first low level tier is exhausted, have them escalate the issue to the engineers. You can also provide Apple with product feedback & maybe if enough people also do the same...maybe Apple will decide to look into the problem (doubtful since it is not easy to reproduce on demand).
