The description says:
Up to ten berries appear in your hand and are infused with magic for the duration. A creature can use its action to eat one berry. Eating a berry restores 1 hit point, and the berry provides enough nourishment to sustain a creature for one day.
The berries lose their potency if they have not been consumed within 24 hours of the casting of this spell.
How should I read "up to ten"? Should I roll d10, or does it depends on the spell slot, or can the caster decide how many berries it creates? If it is up to the caster, I can't think of a good reason for creating less than ten.