I was facing similar issue, the scenario was almost similar, I created some records in database before updating the Prisma Schema, and in another branch I updated the Prisma schema for a model to have a different shape, so now when I try to run findMany() command it get the same error, I manually added filtered the records for missing fields and updated as per latest schema and it's working now

What's Happening:

When you change your Prisma schema. For instance, if you made the updatedAt field non nullable, but some records have null or missing values for this field, Prisma will throw an error when trying to process these records.

How to Fix It:

1. Backup Your Database: Before making any changes, ensure you have a backup of your data.

2. Identify Problematic Records: Use a MongoDB compass to find records missing the required fields. To find records with a null updatedAt field in the carts collection:

   db.carts.find({ updatedAt: null });

3. Update These Records: Add a valid value to the problematic field. You can set updatedAt to the current datetime:

   db.carts.updateMany(
     { updatedAt: null },
     { $set: { updatedAt: new Date() } }
   );

Repeat this process for other collections if necessary.