@kreyren I think it was a hard reset with the power button, some hours after that I turned on the laptop and got an error message. Right now I'm creating a backup, but I can't tell if it's really working.

@lmedinar nah SSDs and modern systems are not vulnerable to hard reset to cause this kind of data corruption, that would only halt an ongoing data transfer that would most likely fixed itself once the system is turned on again.

I am 80% sure that this is an over-heating of the SSD (which is very common) as the technology is very reliable and robust, but the manufacturers are engineering it to fail after the warranty through e.g. using a special graphite mix thermal pad that deteriates over the time.

The solution at least on 2.5" is to open them and replace the thermal pad with a thermal paste.

@kreyren the backup ended correctly some moments ago. Tomorrow I'll try to add some thermal paste before reinstalling the OS just to make sure it won't fail again for a while.