I'm trying to remove all of strings that match occurrences in the array of 'interestedStudents' in a Mongoose schema.

My Mongoose schema looks like this:

// Create a schema.
const schema = new mongoose.Schema<Post>({
    interestedStudents: {
        type: [{
            type: String,
            unique: true
        }],
        required: false,
    },
})

//Create model
export const PostModel = model<Post>('Post', schema);

I'm trying to remove by using:

await PostModel.updateMany({ interestedStudents: { $pullAll : [userId]}})

But I'm getting the following error:

"CastError: Cast to [string] failed for value "[ { '$pullAll': [ '62854109cf9a6db1fcf0393b' ] } ]" (type string) at path "interestedStudents.0" because of "CastError"\n at model.Query.exec

What am I doing wrong? Is my Schema set up wrong? Maybe it's not an array of string?