Overthrowing a regime in a bloody revolution is not merely "changing leadership" and there's a long tradition of waiving "odious debts" incurred by despotic or colonial regimes that have been overthrown in wars of liberation.

https://en.wikipedia.org/wiki/Odious_debt

The concept of odious debt was formalized in a 1927 treatise by Alexander Nahum Sack, a Russian émigré legal theorist. It was based on two 19th-century precedents—Mexico's repudiation of debts incurred by Emperor Maximilian, and the denial by the United States of Cuban liability for debts incurred by the Spanish colonial regime

There are many examples of similar debt repudiation.[8] Chief Justice William Howard Taft, acting as an arbiter, used the doctrine to find that Costa Rica did not have to pay the United Kingdom debts incurred by the Federico Tinoco Granados regime.