This is even more of a knock to Microsoft but the overheating during sleep issue can affect any windows laptop made in the last 5 or so years. The cause is nothing surface specific, it’s Microsoft enforcing “Modern standby” and blocking S3/S4 sleep states in windows. My best understanding is that some bug causes the system to stay awake after one of the periodic wake ups to check for updates/notifications that happen in modern standby.
My work laptop just started doing this 3 weeks ago! It's insane. Rather new machine too.
It gets so hot in my bag I actually worry about it starting a fire one day. I now take it out every night.
Obviously I tried googling but no dice. Nothing changed, settings seem in order, no idea what to do.