short rest spell slots
Concentration spells with long durations - Rules & Game Mechanics ...
You regain all expended spell slots when you finish a long rest.
Warlock - bg3.wiki
Very closely related (about using Warlock slots to generate Sorcery Points, not using Sorcery Points to make Warlock slots): Can I use Pact Magic spell slots gained on a short rest to gain sorcery points?
Unlocking the Magic of DnD Spell Slots_ A Guide for Players and ...
All spellcasters regain spell slots during a long rest – except the DnD Warlock, who can also do so during short rests. Other classes get some long rest buffs too, though.