It does not seem like you want to explicitly ban the pitcher of alchemy, but make sure that it is not used to excess. As GM, you have many tools to encourage other behaviors.
Descriptions, descriptions, descriptions
There is at least You can describe two situations that will encourage diversity among your players.
- Describe the meal time for the characters
When you describe the meal time, point out the monotony of the alchemic jug's approach. It's the same meal over and over again. Players are tired of hearing the same description over and over again.
- Describe the smells that the characters encounter
When describing an area, be sure to insert the smells and tastes that the characters will encounter. Meeting an NPC at a campground should clear the smell of rabbit roasting on the fire. Walking in the forest, you can smell feces indicating good hunting grounds. Upon entering an inn, you can smell the smell of pies floating in the kitchen. A detailed description of the food they see can further encourage the desire to real food.
Do not forget that you can award inspiration to reward a good role play. Consider rewarding the inspiration if you argue about the monotony of the alchemic jug's approach.
Add NPCs to the group
Whether during a rescue or escort mission or a random encounter, increase the size of the group to make the approach of the alchemic pitcher impossible. They will have to rely on additional means to support themselves and their NPC companions. This can be through the Create Food and Water or Goodberries spell or the hunt.
NPCs meeting the party will probably notice the lack of rations by the party and become curious. If the party is not discreet with their pitcher, it may very well ask questions about what the pitcher does and encourage them to show the properties of their pitcher. In the desert, it will be a valuable commodity and could also attract the attention of the less desirable types.
Dead Magic Zones
The group can find areas of dead magic on their travels. Magic items have their properties removed when they are in this area. I would use this sparingly given the craftsmen's reliance on magic items, but it would be a nasty surprise to find that their pitcher is not working.
Add food and water to items found during looting or meetings. Simply finding these objects in the wild can encourage the group to pause in the approach of the alchemy pitcher.
Let the players try this approach. If they end up recovering, you can use it for anchor points. A party who relies on a trick will have to be creative when this trick is stolen or rendered ineffective.
It should be noted here that the perfusion of magical replication objects requires the infusion of an object of the appropriate type. For the Alchemy pitcher, a 1 gallon non-magic ceramic pitcher is probably the appropriate item to require. If they do not carry a spare pitcher, they can not replicate the pitcher's alchemy.
In addition, when the Alchemy vase is replicated, the previously infused vase loses its magical properties. By allowing the artificers to play, you or your players can take advantage of it. Sell the infused Magic article and reproduce it in the morning. The previous one Magic the article is now commonplace and the party (or conman) profited without loss. Just be sure to add bonuses when this trick is discovered.