Officiciaially.

https://www.instagram.com/imgflipai/
Take this account's legitimacy with a grain of salt, as although it linked Imgflip's real creative tools in the profile description (eg. Meme Generator and GIF Maker), indicating some legitimacy, Imgflip themselves has not linked an Instagram account to completely prove its legitimacy, even if the account isn't made to scam people.

It's run by us, but more of a side fun account, not official announcements or anything

It was a good choice featuring AI memes. They're hilarious!

A side fun account.
very cool 👍

I’ve always wondered what the purple M means anyway?

It means that the user is a Global Moderator.

TL;DR: This account's "Officiciaially" status is disputed.