I have used Instagram since before Yuckerberg sucked it into his maw. The reason young folks abandoned it is for the same reason they left Facebook.

At the start, I used it to share photography, and more recently my collage work with a nice small virtual community of artists. There isn't any meaningful alternative to this kind of virtual community. But the changes are annoying. My feed is about 50% folks I follow and 50% sponsored content ads.

And its UI STILL has an easily fixed flaw: enlarging the tap zones around like, comment, and share under each post.