Investigate diff between staking-payouts results vs staking.nominators call (targets)

[Imod7]

Description
Investigate why the validator addresses returned by Sidecar's staking-payouts endpoint do not always match those retrieved from the staking.nominators call -> targets field. While the number of entries is consistent, not all addresses appear in both results. This discrepancy is not necessarily a bug so this issue has been opened to understand the underlying logic.

Steps to Reproduce
Sidecar request
https://polkadot-public-sidecar.parity-chains.parity.io/accounts/15j4dg5GzsL1bw2U2AWgeyAk6QTxq43V7ZPbXdAmbVLjvDCK/staking-payouts

returns

{
  "at": {
    "height": "21083723",
    "hash": "0x656c0b3e888430fc6f1f1900df20a059d16dbe7f1119c8c698db936d2d5e758f"
  },
  "erasPayouts": [
    {
      "era": "1463",
      "totalEraRewardPoints": "31468160",
      "totalEraPayout": "3861854409796879",
      "payouts": [
        {
          "validatorId": "16fmwCAoqJdVtmj7wGEGuFa24WT7x974ZEQsa42x8k9uop1o",
          "nominatorStakingPayout": "11340102541795",
          "claimed": false,
          "totalValidatorRewardPoints": "105400",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28126449916859119",
          "nominatorExposure": "25956323565534164"
        },
        {
          "validatorId": "15ZvLonEseaWZNy8LDkXXj3Y8bmAjxCjwvpy4pXWSL4nGSBs",
          "nominatorStakingPayout": "12329615130151",
          "claimed": false,
          "totalValidatorRewardPoints": "106420",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28126017830660242",
          "nominatorExposure": "27950293004354102"
        },
        {
          "validatorId": "1CUBGfKnpHCW1AZbdJGGj1dihn4QNZ623THYs59r6yuPEMq",
          "nominatorStakingPayout": "10072770397413",
          "claimed": false,
          "totalValidatorRewardPoints": "103900",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124764559480449",
          "nominatorExposure": "23386979860786085"
        },
        {
          "validatorId": "15kkg1mK1tCGgqqo3c1CghtKCQsBEAPPjYNNmmRT3r29FeRX",
          "nominatorStakingPayout": "10857593131697",
          "claimed": false,
          "totalValidatorRewardPoints": "106600",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28126793702637359",
          "nominatorExposure": "24572449253517342"
        },
        {
          "validatorId": "1LUckyocmz9YzeQZHVpBvYYRGXb3rnSm2tvfz79h3G3JDgP",
          "nominatorStakingPayout": "7544076767191",
          "claimed": false,
          "totalValidatorRewardPoints": "103260",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28123011014396133",
          "nominatorExposure": "17623316955540395"
        },
        {
          "validatorId": "1JoBYyPoUdsuU7vZi3KgQAaQYn6WhKqUDXRDmsaJ8Zgxr4T",
          "nominatorStakingPayout": "7722762990094",
          "claimed": false,
          "totalValidatorRewardPoints": "106220",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124602463315772",
          "nominatorExposure": "17538994864844029"
        },
        {
          "validatorId": "132XjckpT4rxeYgFxyJn1QdpbeXmG7arFwfnHs7LVS2VVjzh",
          "nominatorStakingPayout": "11274996840325",
          "claimed": false,
          "totalValidatorRewardPoints": "105800",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124898893290529",
          "nominatorExposure": "25708317416427207"
        },
        {
          "validatorId": "15KDFYfFjdqhp3MDFEtHuyu9kLpXbT7k1zjx78MphViFdCaU",
          "nominatorStakingPayout": "8000797803827",
          "claimed": false,
          "totalValidatorRewardPoints": "106060",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28125906005184360",
          "nominatorExposure": "18198691221468536"
        },
        {
          "validatorId": "15iA5hpjUecWBbf38Nfegwmtyux25o3LrGaNodfZDxq5nXXE",
          "nominatorStakingPayout": "8951506930052",
          "claimed": false,
          "totalValidatorRewardPoints": "106880",
          "validatorCommission": "20000000",
          "totalValidatorExposure": "28127450466936252",
          "nominatorExposure": "19587525656467498"
        },
        {
          "validatorId": "15cfSaBcTxNr8rV59cbhdMNCRagFr3GE6B3zZRsCp4QHHKPu",
          "nominatorStakingPayout": "6462094525356",
          "claimed": false,
          "totalValidatorRewardPoints": "105020",
          "validatorCommission": "30000000",
          "totalValidatorExposure": "28164072824452833",
          "nominatorExposure": "14557960952578401"
        },
        {
          "validatorId": "14UBogS2gU4BqNySJK2uXvgwsawucnwg6kHz1vPfxRV6jY81",
          "nominatorStakingPayout": "12145451255181",
          "claimed": false,
          "totalValidatorRewardPoints": "105760",
          "validatorCommission": "4000000",
          "totalValidatorExposure": "28123330822658683",
          "nominatorExposure": "26422575125855244"
        },
        {
          "validatorId": "1q14G2evG5w34dR6YdSuPbkjP5JAourGASmDXYN1Bzn1z9E",
          "nominatorStakingPayout": "12354808850912",
          "claimed": false,
          "totalValidatorRewardPoints": "106160",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124306078907580",
          "nominatorExposure": "28074296078907580"
        },
        {
          "validatorId": "12eKu3VtN7wm2BN8VmuJJvDyJfWNCCQg8QQVcogk5L71wtC3",
          "nominatorStakingPayout": "12333331887350",
          "claimed": false,
          "totalValidatorRewardPoints": "106220",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124461232959637",
          "nominatorExposure": "28009814480139772"
        },
        {
          "validatorId": "15N2nvyikmU96F5wE919Gc6YLAKGtL6NoQ5ixKLeLp4T4LBV",
          "nominatorStakingPayout": "12074807625514",
          "claimed": false,
          "totalValidatorRewardPoints": "106020",
          "validatorCommission": "50000000",
          "totalValidatorExposure": "28124152393496559",
          "nominatorExposure": "27474121198068744"
        }
      ]
    }
  ]
}

Call
staking.nominators for this account 15j4dg5GzsL1bw2U2AWgeyAk6QTxq43V7ZPbXdAmbVLjvDCK

returns

{
  targets: [
    15wnPRex2QwgWNCMRVSqgqp2syDn8Gf6LPGGabRhA8zoohpt
    16JwE96t9MMvWQHuyHntqVyo6Ks97XCK1kHvWumGNLGVJg5p
    12YUDdiZCHE47WqR6etGD4gfdpSUhrRFvASrVhtc1RcbLva8
    14oaTVEjXK23ukZZqJ1cK5YQpewpeoy1aVpfPNigvmPSNHZF
    13foHgXdzr1agokV6Ed9CBHGQG1NpBqvqhmUL7rojcBUBzvq
    12WNzfWXzogo8N27yNuE9T1xXC2VyJYmTqRDuePp2CNJLgPk
    15tfUt4iQNjMyhZiJGBf4EpETE2KqtW1nfJwbBT1MvWjvcK9
    167Pbuy2HvbHshqc7Xtk4cweCXyyZoJLttAsddDuH3tN7Fco
    15ZvLonEseaWZNy8LDkXXj3Y8bmAjxCjwvpy4pXWSL4nGSBs
    127zarPDhVzmCXVQ7Kfr1yyaa9wsMuJ74GJW9Q7ezHfQEgh6
    16fmwCAoqJdVtmj7wGEGuFa24WT7x974ZEQsa42x8k9uop1o
    12bwaiu2AN7944nT1n3VX9UR2F16PuVDbtGC61Wk5DLzQJsc
    16hUkBK3h94uh7682gk7HeTYvPmSa4D1Y2w4KUZh1u1cP5J
    13BeUcLu7hzSTaoKpEtpdqiXKZz6yVfT9exKH6JuTW8RQQvJ
  ]
  submittedIn: 1,464
  suppressed: false
}

The address 16fmwCAoqJdVtmj7wGEGuFa24WT7x974ZEQsa42x8k9uop1o and 15ZvLonEseaWZNy8LDkXXj3Y8bmAjxCjwvpy4pXWSL4nGSBs can be found in both results but the rest appear different. Maybe this is related to the controller ? (result from staking.bonded call)