Issue in single-table design DynamoDB and limit query parameters

I want to be able to limit the fetch elements I am getting in each query, but I am facing the following issue here:

Since I use the single-table design in DynamoDB I am getting only four items here:

enter image description here

If I check the 10 first elements in DynamoDB, I will notice that I am getting the count here, regardless of the items I am filtering in my Scan operation
enter image description here

  async paginate<TEntity>(
    limit = 10,
    start_key: any
    TableName = $env.MAIN_TABLE
  ): Promise<Paginate<TEntity>> {
    Assert.ok(TableName)
    const items= await this.instance.scan({
       TableName
       Limit: limit,
       ExclusiveStartKey: start_key,
       FilterExpression: 'contains(PK, :PK)',
       ExpressionAttributeValues: {
         ':PK': 'QUIZ#'
       }
    })
    return items
  }

Does anyone here know a workaround for this?