Infura calls eth_getBlockByNumber ten times for each eth_call

I am trying to make a simple nextjs API route (https://nextjs.org/docs/api-routes/introduction) that is connected to the Ethereum blockchain to perform a view function (requires no gas) from a smart contract.

I have a system where you can buy the rights to mint a NFT (ERC721), and this functions checks if the user has paid for any collectionIds that is not yet minted.

import Web3 from 'web3'

import { getPaidForCollectionsIds } from '../../database'
const mnemonic2 = 'main check ...'
var HDWalletProvider = require('truffle-hdwallet-provider')

export default async function (req, res) {
  const paidFor = await getPaidForCollectionsIds(req.body.userId)

  if (paidFor.length < 1) return res.json({ data: [] })

  const provider = new HDWalletProvider(mnemonic2, 'https://rinkeby.infura.io/v3/INFURAAPIKEY', 0)
  const web3 = new Web3(provider)

  const TheContractAddress = '0xfbeF...'
  const { abi } = require('../../abis/TheContract.json')
  const KS = new web3.eth.Contract(abi, TheContractAddress, {
    from: '0x5EE...', // default from address
    gasPrice: '20000000000' // default gas price in wei, 20 gwei in this case
  })

  const unminted = []

  await Promise.all(paidFor.data.map(async pf => KS.methods.readCollectionIdIsUsed(pf.collectionId).call().then(d => {
        console.log(d, 'readCollectionIdIsUsed', pf.collectionId)
      }).catch(e => {
         unminted.push(sign)
      })
    )
  }))

  res.statusCode = 200
  res.json({ data: unminted })
}

here is the code from the readCollectionIdIsUsed method in the smart contract:

    mapping (uint256 => bool) collectionIdIsUsed;

    function readCollectionIdIsUsed(uint256 collectionId) external view returns (bool res) {
        require(collectionIdIsUsed[collectionId], 'This signature has not been used');
        res = collectionIdIsUsed[collectionId];
    }

This all works fine, except for that after a while, I reach the 100 000 request limit of infura.

infura top methods

I dont know why it is calling eth_getBlockByNumber 10 times for each call, is this necessary or is there a way around it?