Nintendo Switch ventilation broken?

For two days my Nintendo Switch has been overheating very often (which is very nerdy in the online game). This has never happened before and I have looked to see if anything is different. I noticed that the ventilation of the Nintendo Switch no longer works, but why? I didn't change anything and always made sure that the ventilation didn't cover anything!

Everything will break down at some point, if you still have a guarantee on your switch you can exchange it

I have owned it for more than 2 years…