Terraform - Can't access attributes on a primitive-typed value (string)

I am using terraform to deploy MX records in cloudflare. Created locals and flattened them filtering out different values

locals {
    MXRecordSets = [
        {
            Name =  "example.com.",
            Type =  "MX",
            TTL =  3600,
            MXRecords =  [
                {
                    Value =  "asdsd.l.google.com",
                    Priority = 1
                },
                {
                    Value =  "alt1.asdsd.l.google.com",
                    Priority = 5
                },
                {
                    Value =  "alt2.asdsd.l.google.com",
                    Priority = 5
                }
            ]
        }
    ]
}

locals {
    FlatMXRecordSets = merge([
    for idx, MXRecordSet in local.MXRecordSets:
      {
        for MXRecord in MXRecordSet.MXRecords:
            "${idx}-${MXRecord.Value}" => {
              MXRecordSet = MXRecordSet
              MXRecord =  MXRecord["Value"]
              Priority = MXRecord["Priority"]
          }
      }
    ]...)
}

resource "cloudflare_record" "com_records_mx" {
  for_each = local.FlatMXRecordSets

  zone_id = cloudflare_zone.example_com.id
  name    = each.value["MXRecordSet"].Name
  value   = each.value["MXRecord"].Value
  type    = each.value["MXRecordSet"].Type
  proxied = false
  ttl     = 1
  priority = each.value["MXRecord"].Priority
}

While running terraform apply, I am getting an error which says Can't access attributes on a primitive-typed value (string).

╷
│ Error: Unsupported attribute
│
│   on main.tf line 476, in resource "cloudflare_record" "com_records_mx":
│  476:   priority = each.value["MXRecord"].Priority
│     ├────────────────
│     │ each.value["MXRecord"] is "alt2.asdsd.l.google.com"
│
│ Can't access attributes on a primitive-typed value (string).