Multer super slow upload after recieving post request with images

Question

Hello I'm on a (ReactJs Node Mysql Express) stack, my website has an events tab which the admin could upload to it events. Each event has a cover photo, inner photos, Title, and a brief text. So I send this whole form in a single post request (is it good?)

var fileUpload = multer({ storage:storage,
limits:{fileSize:150*1024*1024}
})

const multipleUpload = fileUpload.fields([{ name: 'coverPhoto', maxCount: 1 }, { name: 'innerPhotos', maxCount: 30 }])

const storage = multer.diskStorage({
  destination: (req, files, cb) => {
    cb(null, '../client/build/imgs/events')
  },
  filename: (req, files, cb) => {

    cb(null, files.originalname)

  }
})

The server does recieve the request perfectly but after multer receives the photos it takes so long to move them to the fs and the reverse proxy would send a 524 error that it took so long knowing that the format is webp and the photos are so small in size.

Any idea why is it taking so long? I tried to move to formidable but I couldn't figure how to retrieve multiple input fields with multiple files in it ( I only succeeded in sending one input not multiple inputs)

Thank you