Battery Draining almost 20% in an hour while asleep (Switch OLED)

UPDATE 10/25: I have confirmed that Airplane mode resolves the problem. This is almost certainly a Nintendo issue based on the latest firmware update. Without Airplane mode, the screen turns off but the console itself never goes to sleep. If kept in a small container it will heat up the same as if it was playing a game. No idea when this will get fixed...

This is a really weird problem I've been having on my OLED Switch the past few weeks. I'm really worried the battery has degraded, but my original switch didn't need a battery replacement for over 4 years. There were a few occasions recently where my switch started updating while in the bag and got really hot while draining battery.

I've been playing Unicorn Overlord and for the past several months I'd leave it sleeping and it would drain maybe 5-6% a day. I'm testing to see if it drains if I just have nothing running. I have tried draining the battery and charging it to full once, and changing joycons. Device doesn't appear to be hot and lasts for a good while at 100% while actually playing the game.

Is there anything I can do to test or fix the issue? Is this a known bug I just haven't seen?