mempool – Why cannot I bumpfee a tx with 19 ancestors?

I’ve a pockets in bitcoin core 25.0 the place one transaction has 19 ancestors and no descendants (the transaction IDs are obfuscated by A-T, the place T is the newest):

$ bitcoin-cli getmempoolancestors T                                                                          
[
  "L",
  "J",
  "S",
  "H",
  "O",
  "R",
  "M",
  "K",
  "I",
  "Q",
  "G",
  "F",
  "P",
  "B",
  "D",
  "N",
  "A",
  "E",
  "C"
]
$ bitcoin-cli getmempooldescendants T
[
]

When I attempt to bumpfee that transaction, I get the next error:

$ bitcoin-cli bumpfee T '{"fee_rate": 418}'
error code: -4
error message:
Unable to create transaction. Transaction has too lengthy of a mempool chain

This appears odd to me. The restrict of 25 unconfirmed transactions is unquestionably not exceeded right here. There’s additionally package deal measurement restriction (max 101kvB), however that is not exceeded both. Here is the mempoolentry:

$ bitcoin-cli getmempoolentry T
{
  "vsize": 144,
  "weight": 573,
  "time": 1701581567,
  "top": 819521,
  "descendantcount": 1,
  "descendantsize": 144,
  "ancestorcount": 20,
  "ancestorsize": 2842,
  "wtxid": "<wtxid of T>",
  "charges": {
    "base": 0.00011887,
    "modified": 0.00011887,
    "ancestor": 0.00150381,
    "descendant": 0.00011887
  },
  "relies upon": [
    "S"
  ],
  "spentby": [
  ],
  "bip125-replaceable": true,
  "unbroadcast": false
}

ancestorcount together with the bumped tx itself is clearly 20, and the ancestor measurement is 2842 vB. Why cannot I bumpfee this transaction?