By RAW goodberry cannot heal. RAI and officials answers are more important than RAW

[Belier]

Thank you for reading. Brevity is not my strong suit.

[1] It can be confusing. If it helps, just keep in mind that the Duration listed in the attribute block of the spell always and only refers to the duration of the spell. If the spell has a non Instantaneous duration, the duration of the spell and the spell effect are normally the same. Instantaneous duration spells are always finished in an instant, but the effect of the spell can last for varying amounts of time. I don’t have a better word than duration for the effect effectiveness time.

[2] Goodberry is strong in the Hands of a Life Cleric, so I can understand a DM being leery allowing it for that reason. A typical standard array built cleric typically has a plus 3 wisdom bonus. So a 1st level Cure Wounds spell heals for 4 to 11 points of healing. Goodberry always provides 10 points of healing, spread across the 10 berries. Goodberry is more reliable healing, but not useful as an emergency heal in combat.

A 1st level Life Cleric with the same wisdom adds 3 more points of healing from DoL (2+spell level)
So Cure Wounds heals between 7 to 14 points. May heal more total than a Druid’s Goodberry, but the two spells can be seen to have some trade off and both be useful.

But a Life Cleric using DoL on Goodberry has created 40 points of healing. And with two 1st level spell slots, he could cast the spell again, creating 80 points of healing spread across 20 berries. By second level, a Life Cleric can do this, and still save his third 1st level slot for emergency combat healing.

Also, even though Goodberry has no additional effect at higher levels, DoL DOES. If you cast Goodberry using a second level spell slot, it counts as a second level spell. So each Goodberry would heal 5 points each, for 50 points of total healing. Each spell level adds one more point to each berry, until reaching 12 points per berry at 9th level, or 120 Hp total. Not saying that is the best use of a 9th level spell. But for comparison, a Cure Wounds at 9th level with DoL and Supreme Healing is doing only 88 points of healing (Assuming + 5 from Wisdom, Supreme Healing maximizes 9D8 to 72, and +11 from DoL)

Probably not game breaking, but I can see a DM not liking the result.

The only way to get 80 healing out of goodberry at level 1 is life cleric, human variant with magic initiate. You cast it before the long rest and after the short rest to have 20 berries for a day. You cannot use your spell slots to cast it and you cannot upcast it unless you multiclass to druid/ranger amd prepare it. Other wise, you have to wait at level 2 for a multiclassing and you will have 3 slots to cast it.