Issue with trying to get entries where IS NULL

model Loan {
  id              String     @id @default(uuid())
  user            User       @relation(fields: [userId], references: [id])
  userId          String
  number          Int
  customer        Customer   @relation(fields: [customerId], references: [id])
  customerId      String
  ornaments       String
  grossWeight     Decimal
  netWeight       Decimal
  estimatedAmount Int
  loanAmount      Int
  interestRate    Decimal
  date            DateTime
  dueDate         DateTime
  createdAt       DateTime   @default(now())
  updatedAt       DateTime   @updatedAt
  repayment       Repayment? @relation(fields: [repaymentId], references: [id])
  repaymentId     String?

  @@unique([userId, number])
}

model Repayment {
  id        String   @id @default(uuid())
  user      User     @relation(fields: [userId], references: [id])
  userId    String
  number    Int
  date      DateTime
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
  loans     Loan[]

  @@unique([userId, number])
}

model Loan {
  id              String     @id @default(uuid())
  user            User       @relation(fields: [userId], references: [id])
  userId          String
  number          Int
  customer        Customer   @relation(fields: [customerId], references: [id])
  customerId      String
  ornaments       String
  grossWeight     Decimal
  netWeight       Decimal
  estimatedAmount Int
  loanAmount      Int
  interestRate    Decimal
  date            DateTime
  dueDate         DateTime
  createdAt       DateTime   @default(now())
  updatedAt       DateTime   @updatedAt
  repayment       Repayment? @relation(fields: [repaymentId], references: [id])
  repaymentId     String?

  @@unique([userId, number])
}

model Repayment {
  id        String   @id @default(uuid())
  user      User     @relation(fields: [userId], references: [id])
  userId    String
  number    Int
  date      DateTime
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
  loans     Loan[]

  @@unique([userId, number])
}

const outstanding = await prisma.loan.findMany({
  where: { user: { email }, repaymentId: null },
});

const outstanding = await prisma.loan.findMany({
  where: { user: { email }, repaymentId: null },
});