That’s the resting / idle voltage, isn’t it?

I notice that after draining batteries in a flashlight, the voltage often recovers a bit (eg. I often test battery capacity on the MC3000 drained to 2.50v, but after awhile, the voltages begins to recover. High-drain good batteries can stay below 3.0v for quite some time after getting drained. But higher-resistance or poor quality batteries tend to jump very quickly up to higher voltages.

Say if I drain to 2.50v, but then let it stay that way for 1 day or several days, will the battery start getting damaged? (the battery voltage probably would have recovered to 3.0v or higher after a few days).