Protected. But get quality seiko protection (Evva or keeppower are inexpressive options).
By the time the overdischarge protection kicks in you are well past the point you should have stopped anyway. Which is 3.0v. Overdischarge protection a safety cutoff to prevent internal damage to the cell. And there is very little capacity left at that point anyway. You won’t get any real light. Plus if you did go lower, under 2v, (using an unprotected cell) then you should to throw out the cell afterwards. HKJ How far can LiIon be discharged?
Use a li-ion only flashlight, with most of them you can see when the cell is getting low (light will get dimmer). Only lights with a boost or buck/boost driver can use a li-ion to empty without telltale dimming near the end. Like a light that takes AA and 14500.