Periodically there is a crash, power surge, or sudden reboot of your computer. Of course, you had SQL Server Management Studio (SSMS) open and you were working on something important. That seems to be the only time there is a crash/reboot. You can lose work that that was open in SSMS but has not saved. There is an AutoRecover feature in SSMS so all may not be lost.
Read on to learn more about auto-recovery. It only restores on crashes, though there are third-party plugins you can get to restore after start. Azure Data Studio restores on restart as well, so kudos to the ADS team for that.