In July 2020, the father of the Russian retired mixed martial arts champion Habib Nur Mammadov died due to complications from his infection with the Corona virus, but his Irish competitor, Conor McGregor, mocked this death with a tweet on Twitter.

After McGregor's defeat by American Dustin Poirier, on the 11th of this month, Nur Mammadov commented on this loss with a tweet in which he wrote, "Good always triumphs over evil. I am very happy with Dustin Poirier's victory. I hope he gets the championship belt by the end of this year."

McGregor did not respond directly to the Russian fighter’s tweet, and waited until yesterday, Tuesday, and decided to respond in a harsh manner, and was interpreted as a mockery of Nur Mammadov’s father, and McGregor wrote, “Covid is good and father is evil?”, But he quickly deleted the tweet.

In turn, former mixed martial arts champion Daniel Cormier said that "the talk of garbage, does not seem to affect Poirier; from his talk about Dustin's wife to Habib's father, it goes far now, and crosses the red lines."

"When you're dealing with death, with Covid and all these other things that we've dealt with over the course of a year and a half, it's all taboo."