I do think they don't use oligarch for all Russian billionaires. For example it isn't used for Tinkov or Durov. In 90s-00s there really were oligarchs, now they use it for the ones that are or were maybe affiliated with government, like the childhood friends of Putin or former KGB/St Petersburg mayor's office employees who all happen to be CEOs of huge companies
I've heard successive stories of oligarchs getting shaken down for money or outright purged by Putin that I don't think Russia is an oligarchy. That implies some collective decision making.
The Ukraine war is madness and reflects a ruler with absolute power.
