First, Gen Z came after millennials' skinny jeans and side parts. Now the intergenerational TikTok fashion scenes have collided once again as a new debate has brought leggings into the fray.

In a now-viral TikTok video from last month, self-dubbed "hot girl anthropologist" Hannah Brown decided to crowdsource how people styled themselves to run errands.

Donning a chunky knitted sweater, plain white sneakers, a pair of regular ol' black leggings, and sunglasses, Hannah asked her followers what they thought of her "going out" fit?

The comments section was a bloodbath, folks.

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Apparently, according to one commenter, "We should all collectively burn our leggings."

Wait, what?

"Let's be honest, they are not flattering on the majority," they continued.

"Flare leggings, regular leggings out diva," another agreed.

A third jumped in, writing, "Primary thing here is the leggings! Go glared leggings (yoga pants). Also Nike is not it anymore. Adidas Sambas or New Balances are the sneakers rn."

Commenters were also buzzing about platform Uggs.

"Def gotta change those leggings to flare leggings + platform uggs + hair in claw clip + small hoop earrings," wrote another. Someone else agreed, adding, "I'm not a hot girl, but I wear 'flared leggings,' cropped sweaters or fitted cropped tops with a cute jacket, and fake platform Uggs."

Being the dedicated hot girl anthropologist she is, Hannah quickly made a followup to alert the masses to this new development.

"Apparently we're not wearing leggings anymore," she reported. "Leggings are for the gym."

"We are wearing flare leggings, aka yoga pants for us millennials. We are wearing them to run errands, and maybe to the gym as well?" she asked. "I don't know, you can't trust me, you know this."

Try not to panic millennials, but Hannah Brown's comments section is not an isolated incident.

The same thing happened to Style Crusader in October. The millennial creator was out there minding her own business making a video about socks, when BAM! Their comments section was flooded with flared legging advocates.

The TikTok movement is growing. New York stylist Liz Teich suggested swapping out normal leggings for flared ones in her "millennial outfit makeover" series.

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So how did flared leggings pop become the trend?

First off, flared leggings aren't new – the early 2000s knew them as the hugely popular yoga pant trend.

One hilarious video proves the point: Content creator Jenna Barclay voiced the thoughts of her confused millennial peers by pitting "2009 yoga pants girl" against "2023 flared legging girl." The former donned sports bedazzled yoga pants, a Victoria's Secret PINK tank, and a Walkman. The latter joins the chat wearing flared leggings, a black sports bra, and carrying a yoga mat and a bottle of green juice.

"I like your pants," 2023 girl says.

"My yoga pants? Thanks!" replies 2009 girl excitedly. "These are my favorites because they have rhinestones on the waistband."

2023 girl is visibly horrified as the characters spar back and forth about what the style of pants is called.

Yet there still seems to be some heated debate on the matter. Case in point? A handful of Gen Alphas grilled by the Toronto Star were decidedly anti-flare.

Keep your eyes peeled for new developments on the leggings – err, yoga pants? – front, and we'll keep following this hip-hugging fashion debate as it unfolds.