MongoError: BSON field ‘update.updates.u’ is the wrong type

I got this error when I trying to run this code with mongoose for MongoDB

'MongoError: BSON field 'update.updates.u' is the wrong type 'array', expected type 'object''

mongoose version: 5.13.14
mongo version: 5.0.3

    const docs = names.map(name => {
        return {
            updateOne: {
                filter: {
                    name
                },
                update: [{
                    $set: {
                       'data.someData': {
                            '$cond': {
                                if: {
                                    $eq: [
                                        '$data.someData',
                                        undefined
                                    ]
                                },
                                then: extraData.someData,
                                else: undefined
                            }
                        },
                    }
                    }],
                upsert: true,
            }
        }
    })
    await this.myCollection.bulkWrite(docs)