When it comes to the propaganda war, this is a master level move.
Russia has been hyping up the Oreshnik as a nuclear capable missile that can not be easily destroyed by anti-air. Its been a cornerstone of their nuclear propaganda to put fear into Ukraines allies. Its reportedly mostly an old Soviet era missile with a few new parts.
Ukraine created the flamingo as a long distance cruise/drone missiles to strike deep into Russia. This was in response to Its allies refusing to give them long distance capabilities due to fear of nuclear reprisals. Its had a lot of skeptics doubting it could get through Russia Anti-air defense and make any significant impact in the war.
So Ukraine goes and proves the effectiveness of the Flamingo by wrecking the main facility for the Russian Oreshnik program.