They changed the rules and didn’t notify anybody first. That would be illegal for anyone else to do. The problem of this is that some brokers will diversify a portfolio with a percentage of “bundled” bonds and you don’t know what part of it you’re getting hosed on. Just re-distributing the losses.
Welcome to the banana republic, laws are for the serfs to follow, as some animals are now more equal than others, the rules do not apply to them.