Ok, it happened again, but I found the root of the problem. My sdb drive is failing. According to its SMART status "Disk has a few bad sectors".
This drive is a 2 TB Western Digital which I use as NTFS to store multiple heavy things that I use between Linux and Windows, like movies, games, software, backups, etc.
Is there anything I could do?
Running a self-test, this is the result: