As can be observed in this youtube short about a jujitsu technique, this woman's yoga pants are buried so deep into her crack that it's actually separating and magnifying the lobes of her buttocks.
What good can come out of this? A bunch of people on the internet get a dose of ass. The guys at the gym do too, but they have to pretend they're not, because if you're open about being attracted to a woman's ass then you're a creep and making the gym an "unsafe environment." And therein lies the problem. The chick reaps all of the benefits - attention, e-fame, simping - while dealing with none of the consequences - attention from guys she doesn't want to deal with at the moment.
For some reason, the modern woman's brain isn't offended by thousands of guys staring at her and jacking off behind computer screens, but is offended when she's aware of guys staring at her in person. This simple phenomenon is at least half the reason the internet has degraded to its current state. If their thinking were more consistent, we wouldn't have this dilemma. But alas.
Likely, the difference is in the level of threat. Guys on youtube can't contact her, but guys in person might potentially molest her. Unfortunately there's no way to expose yourself to only guys on youtube, but children and modern women both reject reality as unfair, so that doesn't matter.
Meanwhile, the men in the gym have to constantly censor themselves, while suppressing their natural tendency to grab naked cheeks that are being presented to them, and all they get out of it is being able to check out some girl occasionally. I tried to think of a more euphemistic way to phrase this, but ultimately I don't see a point. It is what it is.
The funniest thing about this situation is that all the way up until something does happen, everyone involved will usually swear that everything is normal and only a crazy person would see any problem with a woman coming into a grappling environment in body paint. I can almost guarantee the chick is shagging the coach demonstrating (or some other alpha jujitsu guy there) who will bring down the hammer on anyone getting "creepy," which will work on the surface until the incidents of homewrecking affairs or guys getting too close to her or some random guy oil checking her in a roll become too high to ignore and then the entire thing blows up on Instagram. But until then, you're an incel if you see anything wrong with this.
If you start waving porn magazines in people's faces in a public environment, you get arrested. Anyone wearing yoga pants should get thrown in jail as well.
The problem is that yoga pants have an illusionary affect as I can guarantee 60% of the time their ass does not look as good without yoga pants as in them.
Women have mastered the way to make their body seem even better just from clothing from stockings, skirts, blouses, jeans etc and yoga pants are just the current day meta build.
As for in person vs online, they can easily monetize online whereas in person unless the guy appeals to them, it'll always be interpreted as unwelcome as there isn't a benefit in ego or a relationship having you admire them otherwise.
For my part I think most yoga pants don't even make asses look good. They blend the shading in a weird way. But it's the closest thing to walking around naked in public, so popularity is guaranteed.
Those aren't regular yoga pants. They're scrunch butt leggings. They have a Y shaped seam that starts from the hips, converges between the cheeks, and then goes down to the crotch. The seam is designed to make the butt look rounder and create that wedgie/separation of the cheeks effect, as opposed to the flat "unibutt" effect that traditional leggings/yoga pants give.