How to cascade delete properly in a self-relation with mongodb ?

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "mongodb"
  url      = env("DATABASE_URL")
}

model Tag {
  id           String   @id @default(auto()) @map("_id") @db.ObjectId
  name         String
  Parent       Tag?     @relation("Children", fields: [parentId], references: [id], onUpdate: NoAction, onDelete: NoAction)
  parentId     String?  @db.ObjectId
  Children     Tag[]    @relation("Children")
}

async function getAllChildren(
  prisma: PrismaClient,
  tag?: Prisma.TagGetPayload<object>
): Promise<Prisma.TagGetPayload<object>[]> {
  if (!tag) return [];
  const childrenTags = await prisma.tag.findMany({
    where: { parentId: tag.id },
  });
  const subTags = (
    await Promise.all(childrenTags.map((tag) => getAllChildren(prisma, tag)))
  ).flat();

  return [tag, ...subTags];
}

const allTags = await getAllChildren(
prisma,
await prisma.tag.findUnique({
  where: { id: request.params.tagId },
})
);

const tagsIds = allTags.map((t) => t.id);
return prisma.tag.deleteMany({
where: {
  id: { in: tagsIds },
},
});