EstimateSmartFee returning same amount, regardless of conf_target Running 18.0 on Testnet, fully synced at 1541869 blocks.

bitcoin-cli estimatesmartfee 10

{
  "feerate": 0.00001014,
  "blocks": 10
}


bitcoin-cli estimatesmartfee 50

{
  "feerate": 0.00001014,
  "blocks": 50
}


bitcoin-cli estimatesmartfee 1000

{
  "feerate": 0.00001012,
  "blocks": 1000
}


bitcoin-cli getblockchaininfo

  "verificationprogress": 0.9999922066691247,
  "initialblockdownload": false,
  "size_on_disk": 24450857625,


Any ideas? Thanks
This is expected behavior, especially on testnet. The fee estimator will often return the same fee rate estimate for confirmation targets after a certain value because there isn't enough or any data about transactions confirming at those confirmation targets. So it falls back to the highest confirmation target that it can estimate for and uses that for confirmation targets than that.

Also, you are on testnet which does not really have a fee market, and whatever fees it may have are probably bogus. Thus any fee estimates are also bogus.