Usman vs Covington did around 300k. It was all of the media a few days after the fight, I don't know why I can't find it anymore. It took me a while to find the numbers for UFC 258. I know, you'll probably dismiss me to win an argument, but I believe the fighter payouts for both events can shade some light on the ppv numbers.
At UFC 258 Usman made 3 X what he did for UFC 245.
https://www.mmascene.com/news/ufc-245-payouts-bonuses/
https://mmasalaries.com/ufc-258-salaries-and-payouts/
Usman has distinguished himself as a main event attraction as his last 3 shows, what evidence do you that Covington has done the same? You can't just make that kind of assumption when Covington has only fought ones since he shared the octagon with Usman. His fight against Woodley was a dud.
Here is the fighter payout for that event.
https://thesportsdaily.com/2020/09/...woodley-fighter-salaries-incentive-pay-fox11/
Usman now is his own man, with his own identity. Covington's whole identity is based on his losing effort against Usman. Covington has to attach his name to Usman to gain relevance. Meanwhile there are several memorable events that you cite to talk about Usman not involving Covington.
1.) His dominance of Tyron Woodley.
2.) His comeback stoppage of Gilbert Burns.
3.) One of the greatest knockouts in UFC history which he displayed against Masvidal.
Usman's understand his position and power, that's why he doesn't even acknowledge Covington. He just lets that loudmouth bark while he and his manage handle business behind the scene. He treat Covington like the troll he is.