Not certain if you're reaching for this one but going to just jump on it anyway because it's been brought up before.
No one in Naruto is near lightspeed. I've literally done the debunking work on this one myself previously.
The term 'density' is my terminology, sure, but it's the best way for me to communicate what makes sense to me. When Gai prepares the Night Gai attack, his chakra goes from being a regular eight gates type aura to a giant rampaging beast monster thing that other characters find it hard to even be in the presence of. Madara explicitly mentions the chakra on the page you've posted. He's like "I'll acknowledge your chakra, you're the best at Taijutsu,"It would be compelling if that area were the only place where space bends, but the manga doesn't show this either way--the panel zooms in because it's the only spot that matters to the fight.
https://imgur.com/a/ja5adTs
While Madara is impressed by the chakra, there is no mention of its "density" at any point in the fight. He does mention speed though, immediately before the space-bending feat itself. I think that makes it very clear how we're supposed to read it.
He says Gai is fast but Gai has been being fast the entire fight. Not a few chapters prior to this particular moment, Gai was doing coordinated attacks on all sides with himself. Madara going "Hmm, he's fast," and then going "Wtf space is bending," doesn't automatically mean that the two are linked.
For my money, the space bending thing is not a product of Gai's speed. He doesn't seem to be moving particularly faster than he was previously given how Madara seems to react to it and the only thing that really changed is that his body is clearly giving off a metric ton more chakra than before because of this move.