Yak-9U also saw service with the NK air force as well as the Yak-11 and Yak-16.
Do you have source for Yak-9U being there? I haven't seen one. Several lesser Yak-types were flown, yes.
Also note for the person said that the La-7 didn't see action, well on 06/29/1950, a B-29 damaged a Yak 9 and a La-7.
Finns also claimed to have shot down Spitfires, P-51s and even a P-38 during WWII, yet none of them appeared on our front. Misidentification of enemy types in a war is common place. That article for example talks about Yak-3 which certainly wasn't in Korea. It is a written with the knowledge of that time. I haven't heard of any NK/USSR units that used La-7s in the war, there's plenty of La-7 claims though.