Just to add my experience:
I use wireless but I plugged my switch in, using a standard USB C cable, turned it off, had it set for automatic screen turn off, placed it into a case and came back to the screen being on for ~hour. The case was warped, the air vents broke on the top. I got scared and put it in the freezer.
Not the same. I've had it fixed due to controller problems and I think they replace a lot of things.
I'm just wondering if there are flaws. Flaws that prevent it from shutting down at high temps. I've never seen that again but I triple check. I thought I would charge and protect the screen. I got mine at launch, so I wonder if the initial batches had flaws (I assume likely).
And Nintendo fixed my joy cons (which were the problem) and fixed other things. New screen (mine had a protector, got it back with no scratches, no protector), replaced sir vents. The heat even warped the console plastic so the lines were off. Now it looks brand new. Even need to buy more screen protectors.
I'm wondering why they would fix other things. Has that been a policy or are they being proactive in fixing a bunch of flaws?
I bring this all up because I wonder if we'll find other reasons it heats up.