Karen Khachanov's father is Armenian and his post-match messages are in support of his father's country in their clash and dispute with Azerbaijan.
Karen Khachanov once again references Artsakh following his win at the Australian Open win over Nishioka. The Russian has left a couple of messages on the cameras in reference to that with a reason. As stated above, his father is Armenian and he was always proud to state his Armenian roots.
Artsakh is a disputed region between Armenia and Azerbaijan, officially recognised as part of Azerbaijan but governed by the self-proclaimed Republic of Artsakh. It's a non-recognized state with an Armenian majority within the borders of Azerbaijan. The countries have engaged in armed conflict over the region with a lot of innocent people being affected by the dispute.
Khachanov once spoke about it (2020):
"Despite the fact that I was born in Russia, I always say that I have Armenian roots. It hurts to the depths of my soul to look at what is happening in the country, which I love very much. Innocent people and even children are dying."