It started when Erika Mackley, a 34-year-old art director from Detroit, posed a tongue-in-cheek question to users on X: “i don’t want to hear your most boomer complaint. what’s your most millennial complaint?”

A “boomer complaint” is a concept that has floated around for a while. Typical ones might include people not working as hard anymore or everyone using their phone too much. Ms. Mackley’s post this week, aimed at a younger generation, prompted a mix of gripes and jokes, with posts about bringing heels back to the club, the golden age of comedy films (think “Horrible Bosses” and “Step Brothers”) and a longing for the return of television shows with 24-episode seasons.

“Everybody’s ringtone should still be a 30 second cut of their favorite song in terrible quality,” wrote Dom Pappagallo, 27, an actor from Boston.

As fellow millennials flooded Ms. Mackley’s replies it became clear that members of her generation were nostalgic for a relatively recent past that already felt far away, when large social issues like misinformation, fragmentation and artificial intelligence seemed less prevalent. And for an era in which social media was a place for harmless banter and fun.

Most of the responses — which were hardly limited to actual millennials — did not reach back to the 1990s, but rather to a prepandemic society, when technology seemed more user friendly and personal finances seemed more manageable.

Some mentioned inflation, with one user commenting on the desire for both avocado toast and a house, referring to a trope of almost a decade ago that said millennials would never be able to afford the latter if they kept buying the former. Others yearned for the days of cheaper Ubers, Chipotle bowls and concert tickets.

Many complaints focused on technology and digital media, drawing attention to just how much the world of social media has changed since millennials were coming of age.

The post came at a time of upheaval in the world of social media. Since Elon Musk bought Twitter in 2022, the platform, now called X, has undergone seismic changes. Facebook has removed fact-checking as Mark Zuckerberg pushes the concept of “masculine energy.” A.I. has transformed how people consume content online. And on Friday, the Supreme Court ruled in favor of a federal law that effectively bans TikTok in the United States starting next week.

But the replies to Ms. Mackley looked back further than the current troubles.

Tristan T.A. Hill, 36, a film director from Los Angeles, joked, “The fall of buzzfeed and society collapsing really go hand in hand.”

He remembered when, between 2016 and 2018, BuzzFeed was his go-to source for funny content, and sometimes news, with it all packaged in a millennial’s voice. Now, he said, with “everyone having their own social media and everyone being their own content influencers, it just created a lot more noise.”

“And then with the A.I. stuff, you don’t even know what to trust anymore,” Mr. Hill added. “The misinformation is going crazy.”

Shaelyn Avalon, a 28-year-old singer in Los Angeles, whose millennial complaint was about QR codes at restaurants, commented on the increased segmentation of social media.

“Group think has been a lot heavier on social media the past couple of years,” she said, which to her feels different from when she first created a YouTube channel in 2013.

According to X’s metrics, Ms. Mackley’s post soliciting complaints was seen more than 50 million times.

“Our generation kind of drew the short stick a little bit,” she said in a phone interview. “I’m in my 30s. We’re getting older and it seems like, compared to our parents, we’re not where we’re supposed to be. A lot of the responses I saw were, ‘We’re probably never going to own a home’ and ‘We’re working these insane hours.’”

A “millennial complaint,” she said, is “about not being able to get ahead,” with a dose of humor. “Millennials seem to process things through memes.”

Inflation and rising costs have been dampening morale, and perhaps a post like this drew so many replies because people are yearning for a time when things felt easier and more relaxed. Every generation is wary of changes, and now, with most millennials over 30, it’s their turn to express their grievances, Ms. Mackley said.

Ms. Mackley said she felt nostalgic reading through the responses, including one comment about the decline of flash games. “I remember going on Nickelodeon’s website and playing the ‘Hey Arnold!’ game growing up,” she said.

“People were reliving their youth and their pre-30 days,” Mr. Hill said of the responses, adding that he often reminisces on times when people danced more at parties and when going out was less expensive.

“I’m just not able to do the things that I thought were so much fun back then because there’s more restrictions and it’s more expensive to be outside now,” he said. “I always have friends that joke it costs $100 to leave the house.”

Ms. Mackley said that though she feels like “things are going downhill,” she wonders: “Is it just because I’m getting older?”

“The older generation always feels that way, right?,” said Cathy Carr, 63, a writer from Montclair, N.J. whose “millennial complaint” was about ghosting. “I mean, my father felt that way about us.”