Instagram, facing criticism from Kylie Jenner and others, tries explaining itself.

Instagram versus the Great Celebrity Gang-Up?

The photo-sharing app, which is owned by Meta, found itself under fire this week over how it has changed over time. The pile-on started on Monday, when Kylie Jenner, the beauty mogul with 361 million Instagram followers, shared an image on the site that read: “Make Instagram Instagram again. (stop trying to be tiktok i just want to see cute photos of my friends.) Sincerely, everyone.”

With a “PLEASEEEEEEE” on her Instagram Story, Ms. Jenner, who has the third most followers on the platform, lit the flame of celebrity criticism.

“PRETTY PLEASE,” Kim Kardashian, Ms. Jenner’s half sister and the seventh most followed Instagram user, echoed in a later Story.

On Tuesday, Adam Mosseri, the head of Instagram, tried to tamp down ire from users over how the app has rolled out features that make it more like TikTok, the hugely popular Chinese-owned video app. Instagram has been concerned that TikTok is stealing attention from its users.

To prevent a decline, Instagram recently began tests where videos were prioritized in user feeds and photos and videos took up the whole screen, from top to bottom, instead of a portion of it. Last week, it announced that all videos would be posted as Reels, which were introduced as short video montages, and launched features that encourage collaboration with other users.

In a post on Tuesday, Mr. Mosseri said Instagram was shifting to video and that people liked and shared more videos than photos, irrespective of changes to the platform. “I need to be honest,” he said. “I do believe that more and more of Instagram is going to become video over time.”

Mr. Mosseri said Instagram was just in the early stages of the change. “I also want to be clear. It’s not yet good,” he said of the update.

Celebrities like Ms. Jenner and Ms. Kardashian, who are savvy about social media, have been irritated by changes on other platforms before — and have had an effect. In February 2018, after Snapchat updated its interface to require users to swipe between screens to access different features, Ms. Jenner tweeted: “sooo does anyone else not open Snapchat anymore? Or is it just me… ugh this is so sad.”

Within a week, Snap, Snapchat’s parent company, had lost $1.3 billion in market value.

After Ms. Jenner and Ms. Kardashian made their displeasure about Instagram known on Monday, other celebrities jumped in.

“we don’t wanna make videos Adam lol,” tweeted Chrissy Teigen, a model and author with 39 million Instagram followers, in response to Mr. Mosseri’s post.

James Charles, a beauty YouTuber who has 23 million Instagram followers, also piped up in an Instagram comment. “The reason there’s so much growth for video is because we are being FORCED to post video … The shift to video is not industry wide, it’s TikTok-wide,” he said.

A spokeswoman for Instagram said, “We don’t have much else to share on the changes beyond what Adam stated.”