Submitter: Replacement transactions might not be accepted in mempool

[Lazar955]

Replacement transactions might be rejected due to:

1. Non-standard transactions.
2. Failure to meet Replace-by-Fee (RBF) minimum feerate.

Issue Details

In resendSecondTxOfCheckpointToBTC, if the required replacement fee exceeds the change output, the entire change is used as fees. This can result in a dust output, making the transaction non-standard.

Additionally, since fees are capped by the change output, the transaction may fail to meet RBF minimum feerate. There are also no validations ensuring that the replacement fee is greater than the sum of the original transactions or that it covers the bandwidth cost.

Recommendation

1. Ensure replacement transactions do not produce dust outputs.
2. Validate that replacement transactions meet the minimum required feerate.
3. Implement additional checks to ensure compliance with mempool replacement policies.

BP2-019