Lookup historic account data for a particular round has been dropped?

Hi all, has this feature been dropped? Shouldn’t it be somehow marketized towards the users before publishing to public indexer nodes?

https://algoindexer.testnet.algoexplorerapi.io/v2/assets/48806985/balances?round=19650924
returns now

{
  "message": "Unknown parameter detected: round"
}

Funny thing is that algoexplorer swagger still shows the round as a field.

Anyone has any advise how to detect the balance of specific asa at specific round for 1000 accounts?