isExplicitlyRbf
Returns true
if the transaction itself opted in to be BIP-125-replaceable (RBF).
Warning
Incorrectly relying on RBF may lead to monetary loss!
This does not cover the case where a transaction becomes replaceable due to ancestors being RBF. Please note that transactions may be replaced even if they do not include the RBF signal: https://bitcoinops.org/en/newsletters/2022/10/19/#transaction-replacement-option.